diff --git a/EasyReflectometryApp/Backends/Mock/Plotting.qml b/EasyReflectometryApp/Backends/Mock/Plotting.qml
index 537eb221..57e49717 100644
--- a/EasyReflectometryApp/Backends/Mock/Plotting.qml
+++ b/EasyReflectometryApp/Backends/Mock/Plotting.qml
@@ -23,7 +23,22 @@ QtObject {
 
     property int modelCount: 1
 
+    // Plot mode properties
+    property bool plotRQ4: false
+    property string yMainAxisTitle: 'R(q)'
+    property bool xAxisLog: false
+    property string xAxisType: 'linear'
+    property bool sldXDataReversed: false
+    property bool scaleShown: false
+    property bool bkgShown: false
+
+    // Signals for plot mode changes
+    signal plotModeChanged()
+    signal axisTypeChanged()
+    signal sldAxisReversedChanged()
+    signal referenceLineVisibilityChanged()
     signal samplePageDataChanged()
+    signal samplePageResetAxes()
 
     function setQtChartsSerieRef(value1, value2, value3) {
         console.debug(`setQtChartsSerieRef ${value1}, ${value2}, ${value3}`)
@@ -52,4 +67,70 @@ QtObject {
         return '#0000FF'
     }
 
+    // Plot mode toggle functions
+    function togglePlotRQ4() {
+        plotRQ4 = !plotRQ4
+        yMainAxisTitle = plotRQ4 ? 'R(q)×q⁴' : 'R(q)'
+        plotModeChanged()
+    }
+
+    function toggleXAxisType() {
+        xAxisLog = !xAxisLog
+        xAxisType = xAxisLog ? 'log' : 'linear'
+        axisTypeChanged()
+    }
+
+    function reverseSldXData() {
+        sldXDataReversed = !sldXDataReversed
+        sldAxisReversedChanged()
+    }
+
+    function flipScaleShown() {
+        scaleShown = !scaleShown
+        referenceLineVisibilityChanged()
+    }
+
+    function flipBkgShown() {
+        bkgShown = !bkgShown
+        referenceLineVisibilityChanged()
+    }
+
+    // Reference line data accessors (mock implementation)
+    function getBackgroundData() {
+        if (!bkgShown) return []
+        // Return mock horizontal line at background level
+        return [
+            { 'x': 0.01, 'y': -7.0 },
+            { 'x': 0.30, 'y': -7.0 }
+        ]
+    }
+
+    function getScaleData() {
+        if (!scaleShown) return []
+        // Return mock horizontal line at scale level (log10(1.0) = 0)
+        return [
+            { 'x': 0.01, 'y': 0.0 },
+            { 'x': 0.30, 'y': 0.0 }
+        ]
+    }
+
+    // Analysis-specific reference line data accessors (use sample/calculated x-range)
+    function getBackgroundDataForAnalysis() {
+        if (!bkgShown) return []
+        // Return mock horizontal line at background level using sample x-range
+        return [
+            { 'x': sampleMinX, 'y': -7.0 },
+            { 'x': sampleMaxX, 'y': -7.0 }
+        ]
+    }
+
+    function getScaleDataForAnalysis() {
+        if (!scaleShown) return []
+        // Return mock horizontal line at scale level using sample x-range
+        return [
+            { 'x': sampleMinX, 'y': 0.0 },
+            { 'x': sampleMaxX, 'y': 0.0 }
+        ]
+    }
+
 }
diff --git a/EasyReflectometryApp/Backends/Py/analysis.py b/EasyReflectometryApp/Backends/Py/analysis.py
index b14d351d..2ad4fd81 100644
--- a/EasyReflectometryApp/Backends/Py/analysis.py
+++ b/EasyReflectometryApp/Backends/Py/analysis.py
@@ -11,6 +11,7 @@
 from .logic.calculators import Calculators as CalculatorsLogic
 from .logic.experiments import Experiments as ExperimentLogic
 from .logic.fitting import Fitting as FittingLogic
+from .logic.helpers import get_original_name
 from .logic.minimizers import Minimizers as MinimizersLogic
 from .logic.parameters import Parameters as ParametersLogic
 from .workers import FitterWorker
@@ -59,6 +60,25 @@ def _initialize_selected_experiments(self) -> None:
         else:
             self._selected_experiment_indices = []
 
+    def _ordered_experiments(self) -> list:
+        """Return experiments as an ordered list of experiment objects.
+
+        Handles mapping-like storage without assuming contiguous integer keys.
+        """
+        experiments = self._experiments_logic._project_lib._experiments
+        if not experiments:
+            return []
+
+        if hasattr(experiments, 'items'):
+            items = list(experiments.items())
+            try:
+                items.sort(key=lambda item: item[0])
+            except TypeError:
+                pass
+            return [experiment for _, experiment in items]
+
+        return list(experiments)
+
     ########################
     ## Fitting
     @Property(str, notify=fittingChanged)
@@ -278,7 +298,7 @@ def setExperimentNameAtIndex(self, index: int, new_name: str) -> None:
     def modelIndexForExperiment(self) -> int:
         # return the model index for the current experiment
         models = self._experiments_logic._project_lib._models
-        experiments = self._experiments_logic._project_lib._experiments
+        experiments = self._ordered_experiments()
         index = self.experimentCurrentIndex
         current_experiment = experiments[index] if 0 <= index < len(experiments) else None
         if current_experiment is not None:
@@ -290,18 +310,19 @@ def modelIndexForExperiment(self) -> int:
     def modelNamesForExperiment(self) -> list:
         # return a list of model names for each experiment
         mapped_models = []
-        experiments = self._experiments_logic._project_lib._experiments
-        for ind in experiments:
-            mapped_models.append(experiments[ind].model.name)
+        experiments = self._ordered_experiments()
+        for experiment in experiments:
+            name = get_original_name(experiment.model)
+            mapped_models.append(name)
         return mapped_models
 
     @Property('QVariantList', notify=experimentsChanged)
     def modelColorsForExperiment(self) -> list:
         # return a list of model colors for each experiment
         mapped_models = []
-        experiments = self._experiments_logic._project_lib._experiments
-        for ind in experiments:
-            mapped_models.append(experiments[ind].model.color)
+        experiments = self._ordered_experiments()
+        for experiment in experiments:
+            mapped_models.append(experiment.model.color)
         return mapped_models
 
     @Slot(int)
@@ -501,14 +522,10 @@ def enabledParameters(self) -> list[dict[str]]:
         if self._chached_enabled_parameters is not None:
             return self._chached_enabled_parameters
         enabled_parameters = []
-        # import time
-        # t0 = time.time()
         for parameter in self._parameters_logic.parameters:
             if not parameter['enabled']:
                 continue
             enabled_parameters.append(parameter)
-        # t1 = time.time()
-        # print(f"Enabled parameters computation time: {t1 - t0:.4f} seconds")
         self._chached_enabled_parameters = enabled_parameters
         return enabled_parameters
 
diff --git a/EasyReflectometryApp/Backends/Py/logic/experiments.py b/EasyReflectometryApp/Backends/Py/logic/experiments.py
index 3a2dbff9..f292d886 100644
--- a/EasyReflectometryApp/Backends/Py/logic/experiments.py
+++ b/EasyReflectometryApp/Backends/Py/logic/experiments.py
@@ -5,12 +5,41 @@ class Experiments:
     def __init__(self, project_lib: ProjectLib):
         self._project_lib = project_lib
 
+    def _ordered_experiment_items(self) -> list[tuple[object, object]]:
+        """Return experiments as ordered ``(key, experiment)`` pairs.
+
+        Supports mapping-like storage without assuming contiguous integer keys.
+        """
+        experiments = self._project_lib._experiments
+        if not experiments:
+            return []
+
+        if hasattr(experiments, 'items'):
+            items = list(experiments.items())
+            try:
+                items.sort(key=lambda item: item[0])
+            except TypeError:
+                pass
+            return items
+
+        return list(enumerate(experiments))
+
+    def _experiment_at_index(self, index: int):
+        items = self._ordered_experiment_items()
+        if 0 <= index < len(items):
+            return items[index][1]
+        return None
+
+    def _experiment_key_at_index(self, index: int):
+        items = self._ordered_experiment_items()
+        if 0 <= index < len(items):
+            return items[index][0]
+        return None
+
     def available(self) -> list[str]:
         experiments_name = []
         try:
-            # get .name from self._project_lib._experiments and append to experiments_name
-            for ind in self._project_lib._experiments.keys():
-                exp = self._project_lib._experiments[ind]
+            for _, exp in self._ordered_experiment_items():
                 experiments_name.append(exp.name)
         except IndexError:
             pass
@@ -26,19 +55,19 @@ def set_current_index(self, new_value: int) -> None:
         return False
 
     def set_experiment_name(self, new_name: str) -> None:
-        exp = self._project_lib._experiments.get(self._project_lib._current_experiment_index)
+        exp = self._experiment_at_index(self._project_lib._current_experiment_index)
         if exp:
             exp.name = new_name
 
     def set_experiment_name_at_index(self, index: int, new_name: str) -> None:
-        exp = self._project_lib._experiments.get(index)
+        exp = self._experiment_at_index(index)
         if exp:
             exp.name = new_name
 
     def model_on_experiment(self, experiment_index: int = -1) -> dict:
         if experiment_index == -1:
             experiment_index = self._project_lib._current_experiment_index
-        exp = self._project_lib._experiments.get(experiment_index)
+        exp = self._experiment_at_index(experiment_index)
         if exp:
             return exp.model
         return {}
@@ -50,7 +79,7 @@ def model_index_on_experiment(self) -> int:
         return -1
 
     def set_model_on_experiment(self, new_value: int) -> None:
-        exp = self._project_lib._experiments.get(self._project_lib._current_experiment_index)
+        exp = self._experiment_at_index(self._project_lib._current_experiment_index)
         models = self._project_lib._models
         if exp and models:
             try:
@@ -66,12 +95,27 @@ def remove_experiment(self, index: int) -> None:
         """
         Remove the experiment at the given index.
         """
-        if 0 <= index < len(self.available()):
-            del self._project_lib._experiments[index]
-            # readjust the dictionary keys for continuity
-            temp_experiments = self._project_lib._experiments.copy()
-            self._project_lib._experiments = {i: exp for i, exp in enumerate(temp_experiments.values())}
-            if self._project_lib._current_experiment_index >= index:
-                self._project_lib._current_experiment_index = max(0, self._project_lib._current_experiment_index - 1)
-        else:
+        total = len(self.available())
+        if not (0 <= index < total):
+            print(f'Experiment index {index} is out of range.')
+            return
+
+        experiments = self._project_lib._experiments
+        exp_key = self._experiment_key_at_index(index)
+        if exp_key is None:
             print(f'Experiment index {index} is out of range.')
+            return
+
+        if hasattr(experiments, 'items'):
+            del experiments[exp_key]
+        else:
+            experiments.pop(index)
+
+        current = self._project_lib._current_experiment_index
+        new_total = max(0, total - 1)
+        if new_total == 0:
+            self._project_lib._current_experiment_index = 0
+        elif current > index:
+            self._project_lib._current_experiment_index = current - 1
+        elif current >= new_total:
+            self._project_lib._current_experiment_index = new_total - 1
diff --git a/EasyReflectometryApp/Backends/Py/logic/fitting.py b/EasyReflectometryApp/Backends/Py/logic/fitting.py
index 1e71955f..18d683af 100644
--- a/EasyReflectometryApp/Backends/Py/logic/fitting.py
+++ b/EasyReflectometryApp/Backends/Py/logic/fitting.py
@@ -106,6 +106,25 @@ def prepare_for_threaded_fit(self) -> None:
         self._show_results_dialog = False
         self._fit_error_message = None
 
+    def _ordered_experiments(self) -> list:
+        """Return experiments as an ordered list of experiment objects.
+
+        Handles mapping-like storage without assuming contiguous integer keys.
+        """
+        experiments = self._project_lib._experiments
+        if not experiments:
+            return []
+
+        if hasattr(experiments, 'items'):
+            items = list(experiments.items())
+            try:
+                items.sort(key=lambda item: item[0])
+            except TypeError:
+                pass
+            return [experiment for _, experiment in items]
+
+        return list(experiments)
+
     def prepare_threaded_fit(self, minimizers_logic: 'Minimizers') -> tuple:
         """Prepare data for threaded fitting.
 
@@ -115,7 +134,7 @@ def prepare_threaded_fit(self, minimizers_logic: 'Minimizers') -> tuple:
         try:
             from easyreflectometry.fitting import MultiFitter
 
-            experiments = self._project_lib._experiments
+            experiments = self._ordered_experiments()
             if not experiments:
                 self._fit_error_message = 'No experiments to fit'
                 self._running = False
@@ -123,30 +142,44 @@ def prepare_threaded_fit(self, minimizers_logic: 'Minimizers') -> tuple:
                 self._show_results_dialog = True
                 return None, None, None, None, None
 
-            experiment_indices = range(len(experiments))
-
             # Create MultiFitter with all models
-            models = [experiments[idx].model for idx in experiment_indices]
+            models = [experiment.model for experiment in experiments]
             multi_fitter = MultiFitter(*models)
 
+            # Apply the user-selected minimizer to the new fitter
+            selected_minimizer = minimizers_logic.selected_minimizer_enum()
+            if selected_minimizer is not None:
+                multi_fitter.easy_science_multi_fitter.switch_minimizer(selected_minimizer)
+                logger.info(
+                    'Fitting: applied minimizer %s to MultiFitter (engine: %s, method: %s)',
+                    selected_minimizer.name,
+                    multi_fitter.easy_science_multi_fitter.minimizer.package,
+                    multi_fitter.easy_science_multi_fitter.minimizer._method,
+                )
+            if minimizers_logic.tolerance is not None:
+                multi_fitter.easy_science_multi_fitter.tolerance = minimizers_logic.tolerance
+            if minimizers_logic.max_iterations is not None:
+                multi_fitter.easy_science_multi_fitter.max_evaluations = minimizers_logic.max_iterations
+
             # Prepare data arrays for all experiments
-            x_data = [experiments[idx].x for idx in experiment_indices]
-            y_data = [experiments[idx].y for idx in experiment_indices]
+            x_data = [experiment.x for experiment in experiments]
+            y_data = [experiment.y for experiment in experiments]
 
             # Validate error values before computing weights to avoid division by zero
             import numpy as np
 
-            for idx in experiment_indices:
-                ye = experiments[idx].ye
+            for idx, experiment in enumerate(experiments):
+                ye = experiment.ye
                 if np.any(ye == 0):
-                    exp_name = experiments[idx].name if hasattr(experiments[idx], 'name') else f'index {idx}'
+                    exp_name = experiment.name if hasattr(experiment, 'name') else f'index {idx}'
                     self._fit_error_message = f'Experiment {exp_name} has zero error values which would cause division by zero'
                     self._running = False
                     self._finished = True
                     self._show_results_dialog = True
                     return None, None, None, None, None
 
-            weights = [1.0 / experiments[idx].ye for idx in experiment_indices]
+            # ye contains variances (sigma²); weights = 1/sigma = 1/sqrt(variance)
+            weights = [1.0 / np.sqrt(experiment.ye) for experiment in experiments]
 
             # Method is optional in fit() - pass None to use minimizer's default
             method = None
@@ -176,6 +209,8 @@ def on_fit_finished(self, results: List[FitResults]) -> None:
             # For multi-experiment fits, store the list; use first for single-result properties
             self._results = results
             self._result = results[0]
+            engine_name = getattr(results[0], 'minimizer_engine', 'unknown')
+            logger.info('Fit finished: engine=%s, chi2=%s, success=%s', engine_name, self.fit_chi2, results[0].success)
         else:
             self._result = results
             self._results = [results] if results else []
@@ -222,12 +257,12 @@ def start_stop(self) -> None:
                 # Handle fit failure - create a failed result
                 self._result = None
                 self._fit_error_message = str(e)
-                print(f'Fit failed: {e}')
+                logger.warning('Fit failed: %s', e)
             except Exception as e:
                 # Handle any other unexpected exceptions
                 self._result = None
                 self._fit_error_message = str(e)
-                print(f'Unexpected error during fit: {e}')
+                logger.warning('Unexpected error during fit: %s', e)
             finally:
                 self._running = False
                 self._finished = True
diff --git a/EasyReflectometryApp/Backends/Py/logic/helpers.py b/EasyReflectometryApp/Backends/Py/logic/helpers.py
index bb1a90d0..70465a5b 100644
--- a/EasyReflectometryApp/Backends/Py/logic/helpers.py
+++ b/EasyReflectometryApp/Backends/Py/logic/helpers.py
@@ -16,3 +16,14 @@ def formatMsg(type, *args):
         msg = ' ▌ '.join(msgs)
         msg = f'{mark} {msg}'
         return msg
+
+
+def get_original_name(obj) -> str:
+    """Get original name from user_data, with defensive fallback to obj.name.
+
+    Safely handles cases where user_data is None or not a dict.
+    """
+    user_data = getattr(obj, 'user_data', None)
+    if isinstance(user_data, dict):
+        return user_data.get('original_name', obj.name)
+    return obj.name
diff --git a/EasyReflectometryApp/Backends/Py/logic/minimizers.py b/EasyReflectometryApp/Backends/Py/logic/minimizers.py
index b6352b56..0a190dfb 100644
--- a/EasyReflectometryApp/Backends/Py/logic/minimizers.py
+++ b/EasyReflectometryApp/Backends/Py/logic/minimizers.py
@@ -26,12 +26,17 @@ def minimizers_available(self) -> list[str]:
     def minimizer_current_index(self) -> int:
         return self._minimizer_current_index
 
+    def selected_minimizer_enum(self):
+        """Return the AvailableMinimizers enum for the currently selected minimizer."""
+        if 0 <= self._minimizer_current_index < len(self._list_available_minimizers):
+            return self._list_available_minimizers[self._minimizer_current_index]
+        return None
+
     def set_minimizer_current_index(self, new_value: int) -> bool:
         if new_value != self._minimizer_current_index:
             self._minimizer_current_index = new_value
-            if self._project_lib._fitter is not None:
-                enum_new_minimizer = self._list_available_minimizers[new_value]
-                self._project_lib._fitter.switch_minimizer(enum_new_minimizer)
+            enum_new_minimizer = self._list_available_minimizers[new_value]
+            self._project_lib.minimizer = enum_new_minimizer
             return True
         return False
 
diff --git a/EasyReflectometryApp/Backends/Py/logic/models.py b/EasyReflectometryApp/Backends/Py/logic/models.py
index cf2777d2..37bc1e81 100644
--- a/EasyReflectometryApp/Backends/Py/logic/models.py
+++ b/EasyReflectometryApp/Backends/Py/logic/models.py
@@ -5,6 +5,8 @@
 from easyreflectometry.model import ModelCollection
 from easyreflectometry.model.resolution_functions import PercentageFwhm
 
+from .helpers import get_original_name
+
 
 class Models:
     def __init__(self, project_lib: ProjectLib):
@@ -21,7 +23,7 @@ def index(self, new_value: Union[int, str]) -> None:
 
     @property
     def name_at_current_index(self) -> str:
-        return self._models[self.index].name
+        return get_original_name(self._models[self.index])
 
     @property
     def scaling_at_current_index(self) -> float:
@@ -128,7 +130,7 @@ def _from_models_collection_to_list_of_dicts(models_collection: ModelCollection)
     for model in models_collection:
         models_list.append(
             {
-                'label': model.name,
+                'label': get_original_name(model),
                 'color': str(model.color),
             }
         )
diff --git a/EasyReflectometryApp/Backends/Py/logic/parameters.py b/EasyReflectometryApp/Backends/Py/logic/parameters.py
index bc36f539..1cb57160 100644
--- a/EasyReflectometryApp/Backends/Py/logic/parameters.py
+++ b/EasyReflectometryApp/Backends/Py/logic/parameters.py
@@ -9,6 +9,8 @@
 from easyscience import global_object
 from easyscience.variable import Parameter
 
+from .helpers import get_original_name
+
 RESERVED_ALIAS_NAMES = {'np', 'numpy', 'math', 'pi', 'e'}
 
 
@@ -226,7 +228,7 @@ def _is_layer_parameter(param: Parameter) -> bool:
     # Process parameters for each model
     for model_idx, model in enumerate(models):
         model_unique_name = model.unique_name
-        model_prefix = f'M{model_idx + 1}'
+        model_prefix = get_original_name(model)
 
         for parameter in parameters:
             # Skip parameters not in this model's path
@@ -249,6 +251,7 @@ def _is_layer_parameter(param: Parameter) -> bool:
                 prefixed_display_name = display_name
 
             alias = _make_alias(prefixed_display_name or parameter.name)
+            param_value = float(parameter.value)
             parameter_list.append(
                 {
                     'name': prefixed_display_name,
@@ -256,7 +259,7 @@ def _is_layer_parameter(param: Parameter) -> bool:
                     'group': group_name,
                     'alias': alias,
                     'unique_name': parameter.unique_name,
-                    'value': float(parameter.value),
+                    'value': param_value,
                     'error': float(parameter.variance),
                     'max': float(parameter.max),
                     'min': float(parameter.min),
diff --git a/EasyReflectometryApp/Backends/Py/logic/project.py b/EasyReflectometryApp/Backends/Py/logic/project.py
index adf8976c..47ee5be7 100644
--- a/EasyReflectometryApp/Backends/Py/logic/project.py
+++ b/EasyReflectometryApp/Backends/Py/logic/project.py
@@ -122,6 +122,11 @@ def add_sample_from_orso(self, sample) -> None:
         new_model_index = len(self._project_lib.models) - 1
         self._update_enablement_of_fixed_layers_for_model(new_model_index)
 
+    def replace_models_from_orso(self, sample) -> None:
+        """Replace all existing models with a single model built from the loaded sample."""
+        self._project_lib.replace_models_from_orso(sample)
+        self._update_enablement_of_fixed_layers_for_model(0)
+
     def reset(self) -> None:
         self._project_lib.reset()
         self._project_lib.default_model()
diff --git a/EasyReflectometryApp/Backends/Py/logic/status.py b/EasyReflectometryApp/Backends/Py/logic/status.py
index 87ac11ce..89fc2fb7 100644
--- a/EasyReflectometryApp/Backends/Py/logic/status.py
+++ b/EasyReflectometryApp/Backends/Py/logic/status.py
@@ -4,6 +4,10 @@
 class Status:
     def __init__(self, project_lib: ProjectLib):
         self._project_lib = project_lib
+        self._minimizers_logic = None
+
+    def set_minimizers_logic(self, minimizers_logic):
+        self._minimizers_logic = minimizers_logic
 
     @property
     def project(self):
@@ -11,6 +15,11 @@ def project(self):
 
     @property
     def minimizer(self):
+        if self._minimizers_logic is not None:
+            available = self._minimizers_logic.minimizers_available()
+            idx = self._minimizers_logic.minimizer_current_index()
+            if 0 <= idx < len(available):
+                return available[idx]
         return self._project_lib.minimizer.name
 
     @property
diff --git a/EasyReflectometryApp/Backends/Py/plotting_1d.py b/EasyReflectometryApp/Backends/Py/plotting_1d.py
index e06fdf6a..36ee9f88 100644
--- a/EasyReflectometryApp/Backends/Py/plotting_1d.py
+++ b/EasyReflectometryApp/Backends/Py/plotting_1d.py
@@ -19,6 +19,13 @@ class Plotting1d(QObject):
     experimentChartRangesChanged = Signal()
     experimentDataChanged = Signal()
     samplePageDataChanged = Signal()  # Signal for QML to refresh sample page charts
+    samplePageResetAxes = Signal()  # Signal for QML to reset chart axes after data load
+
+    # New signals for plot mode properties
+    plotModeChanged = Signal()
+    axisTypeChanged = Signal()
+    sldAxisReversedChanged = Signal()
+    referenceLineVisibilityChanged = Signal()
 
     def __init__(self, project_lib: ProjectLib, parent=None):
         super().__init__(parent)
@@ -26,7 +33,15 @@ def __init__(self, project_lib: ProjectLib, parent=None):
         self._proxy = parent
         self._currentLib1d = 'QtCharts'
         self._sample_data = {}
+        self._model_data = {}
         self._sld_data = {}
+
+        # Plot mode state
+        self._plot_rq4 = False
+        self._x_axis_log = False
+        self._sld_x_reversed = False
+        self._scale_shown = False
+        self._bkg_shown = False
         self._chartRefs = {
             'QtCharts': {
                 'samplePage': {
@@ -48,9 +63,150 @@ def __init__(self, project_lib: ProjectLib, parent=None):
 
     def reset_data(self):
         self._sample_data = {}
+        self._model_data = {}
         self._sld_data = {}
         console.debug(IO.formatMsg('sub', 'Sample and SLD data cleared'))
 
+    def _apply_rq4(self, x, y):
+        """Apply R(q)×q⁴ transformation if enabled.
+
+        Works with both numpy arrays and scalar values.
+        """
+        if self._plot_rq4:
+            return y * (x**4)
+        return y
+
+    # R(q)×q⁴ mode
+    @Property(bool, notify=plotModeChanged)
+    def plotRQ4(self) -> bool:
+        """Return whether R(q)×q⁴ mode is enabled."""
+        return self._plot_rq4
+
+    @Slot()
+    def togglePlotRQ4(self) -> None:
+        """Toggle R(q)×q⁴ plotting mode."""
+        self._plot_rq4 = not self._plot_rq4
+        self.plotModeChanged.emit()
+        # Refresh all charts with new mode
+        self.sampleChartRangesChanged.emit()
+        self.experimentChartRangesChanged.emit()
+        self.samplePageDataChanged.emit()
+
+    @Property(str, notify=plotModeChanged)
+    def yMainAxisTitle(self) -> str:
+        """Return Y-axis title based on current plot mode."""
+        return 'R(q)×q⁴' if self._plot_rq4 else 'R(q)'
+
+    # X-axis type (log/linear)
+    @Property(bool, notify=axisTypeChanged)
+    def xAxisLog(self) -> bool:
+        """Return whether X-axis is logarithmic."""
+        return self._x_axis_log
+
+    @Slot()
+    def toggleXAxisType(self) -> None:
+        """Toggle between linear and logarithmic X-axis."""
+        self._x_axis_log = not self._x_axis_log
+        self.axisTypeChanged.emit()
+
+    @Property(str, notify=axisTypeChanged)
+    def xAxisType(self) -> str:
+        """Return X-axis type as string for QML."""
+        return 'log' if self._x_axis_log else 'linear'
+
+    # SLD X-axis reversal
+    @Property(bool, notify=sldAxisReversedChanged)
+    def sldXDataReversed(self) -> bool:
+        """Return whether SLD X-axis is reversed."""
+        return self._sld_x_reversed
+
+    @Slot()
+    def reverseSldXData(self) -> None:
+        """Toggle SLD X-axis reversal."""
+        self._sld_x_reversed = not self._sld_x_reversed
+        self.sldAxisReversedChanged.emit()
+        self.sldChartRangesChanged.emit()
+
+    # Reference line visibility
+    @Property(bool, notify=referenceLineVisibilityChanged)
+    def scaleShown(self) -> bool:
+        """Return whether scale reference line is shown."""
+        return self._scale_shown
+
+    @Slot()
+    def flipScaleShown(self) -> None:
+        """Toggle scale line visibility."""
+        self._scale_shown = not self._scale_shown
+        self.referenceLineVisibilityChanged.emit()
+
+    @Property(bool, notify=referenceLineVisibilityChanged)
+    def bkgShown(self) -> bool:
+        """Return whether background reference line is shown."""
+        return self._bkg_shown
+
+    @Slot()
+    def flipBkgShown(self) -> None:
+        """Toggle background line visibility."""
+        self._bkg_shown = not self._bkg_shown
+        self.referenceLineVisibilityChanged.emit()
+
+    def _get_reference_line_data(self, param_attr: str, default_log: float, use_analysis_range: bool) -> list:
+        """Build a horizontal reference line for the given model parameter.
+
+        :param param_attr: Model attribute name ('background' or 'scale')
+        :param default_log: Default log10 value if parameter <= 0
+        :param use_analysis_range: If True, use sample/analysis x-range; if False, use experimental data x-range
+        """
+        try:
+            model_idx = self._project_lib.current_model_index
+            model = self._project_lib.models[model_idx]
+
+            if use_analysis_range:
+                x_min, x_max = self._get_all_models_sample_range()[0:2]
+                if x_min == float('inf') or x_max == float('-inf'):
+                    return []
+            else:
+                exp_idx = self._project_lib.current_experiment_index
+                exp_data = self._project_lib.experimental_data_for_model_at_index(exp_idx)
+                if exp_data.x is None or len(exp_data.x) == 0:
+                    return []
+                x_min, x_max = float(exp_data.x[0]), float(exp_data.x[-1])
+
+            param_value = getattr(model, param_attr).value
+            y_log = float(np.log10(param_value)) if param_value > 0 else default_log
+            return [{'x': float(x_min), 'y': y_log}, {'x': float(x_max), 'y': y_log}]
+        except (IndexError, AttributeError, TypeError) as e:
+            console.debug(f'Error getting {param_attr} reference line data: {e}')
+            return []
+
+    @Slot(result='QVariantList')
+    def getBackgroundData(self) -> list:
+        """Return background reference line data for the Experiment chart."""
+        if not self._bkg_shown:
+            return []
+        return self._get_reference_line_data('background', -10.0, use_analysis_range=False)
+
+    @Slot(result='QVariantList')
+    def getScaleData(self) -> list:
+        """Return scale reference line data for the Experiment chart."""
+        if not self._scale_shown:
+            return []
+        return self._get_reference_line_data('scale', 0.0, use_analysis_range=False)
+
+    @Slot(result='QVariantList')
+    def getBackgroundDataForAnalysis(self) -> list:
+        """Return background reference line data for the Analysis chart (sample x-range)."""
+        if not self._bkg_shown:
+            return []
+        return self._get_reference_line_data('background', -10.0, use_analysis_range=True)
+
+    @Slot(result='QVariantList')
+    def getScaleDataForAnalysis(self) -> list:
+        """Return scale reference line data for the Analysis chart (sample x-range)."""
+        if not self._scale_shown:
+            return []
+        return self._get_reference_line_data('scale', 0.0, use_analysis_range=True)
+
     @property
     def sample_data(self) -> DataSet1D:
         idx = self._project_lib.current_model_index
@@ -67,6 +223,22 @@ def sample_data(self) -> DataSet1D:
         self._sample_data[idx] = data
         return data
 
+    @property
+    def model_data(self) -> DataSet1D:
+        idx = self._project_lib.current_model_index
+        if idx in self._model_data and self._model_data[idx] is not None:
+            return self._model_data[idx]
+        try:
+            data = self._project_lib.model_data_for_model_at_index(idx)
+        except IndexError:
+            data = DataSet1D(
+                name='Model Data empty',
+                x=np.empty(0),
+                y=np.empty(0),
+            )
+        self._model_data[idx] = data
+        return data
+
     @property
     def sld_data(self) -> DataSet1D:
         idx = self._project_lib.current_model_index
@@ -154,8 +326,10 @@ def _get_all_models_sample_range(self):
                     min_x = min(min_x, data.x.min())
                     max_x = max(max_x, data.x.max())
                 if data.y.size > 0:
-                    valid_y = data.y[data.y > 0]
+                    valid_mask = data.y > 0
+                    valid_y = data.y[valid_mask]
                     if valid_y.size > 0:
+                        valid_y = self._apply_rq4(data.x[valid_mask], valid_y)
                         min_y = min(min_y, np.log10(valid_y.min()))
                         max_y = max(max_y, np.log10(valid_y.max()))
             except (IndexError, ValueError):
@@ -167,9 +341,11 @@ def _get_all_models_sample_range(self):
         if max_x == float('-inf'):
             max_x = self.sample_data.x.max() if self.sample_data.x.size > 0 else 1.0
         if min_y == float('inf'):
-            min_y = np.log10(self.sample_data.y.min()) if self.sample_data.y.size > 0 else -10.0
+            valid_y = self.sample_data.y[self.sample_data.y > 0] if self.sample_data.y.size > 0 else np.array([])
+            min_y = np.log10(valid_y.min()) if valid_y.size > 0 else -10.0
         if max_y == float('-inf'):
-            max_y = np.log10(self.sample_data.y.max()) if self.sample_data.y.size > 0 else 0.0
+            valid_y = self.sample_data.y[self.sample_data.y > 0] if self.sample_data.y.size > 0 else np.array([])
+            max_y = np.log10(valid_y.max()) if valid_y.size > 0 else 0.0
 
         return (min_x, max_x, min_y, max_y)
 
@@ -233,13 +409,24 @@ def experimentMinX(self):
     @Property(float, notify=experimentChartRangesChanged)
     def experimentMaxY(self):
         data = self.experiment_data
-        return np.log10(data.y.max()) if data.y.size > 0 else 1.0
+        if data.y.size == 0:
+            return 1.0
+        y_values = self._apply_rq4(data.x, data.y)
+        return np.log10(y_values.max())
 
     @Property(float, notify=experimentChartRangesChanged)
     def experimentMinY(self):
         data = self.experiment_data
         valid_y = data.y[data.y > 0] if data.y.size > 0 else np.array([1e-10])
-        return np.log10(valid_y.min()) if valid_y.size > 0 else -10.0
+        if valid_y.size == 0:
+            return -10.0
+        valid_x = data.x[data.y > 0] if data.y.size > 0 else np.array([1.0])
+        valid_y = self._apply_rq4(valid_x, valid_y)
+        # Filter again after transformation to avoid log of zero/negative
+        valid_y = valid_y[valid_y > 0]
+        if valid_y.size == 0:
+            return -10.0
+        return np.log10(valid_y.min())
 
     @Property('QVariant', notify=chartRefsChanged)
     def chartRefs(self):
@@ -284,7 +471,12 @@ def getSampleDataPointsForModel(self, model_index: int) -> list:
             data = self._project_lib.sample_data_for_model_at_index(model_index)
             points = []
             for point in data.data_points():
-                points.append({'x': float(point[0]), 'y': float(np.log10(point[1])) if point[1] > 0 else -10.0})
+                x_val = float(point[0])
+                y_val = float(point[1])
+                if y_val > 0:
+                    y_val = self._apply_rq4(x_val, y_val)
+                y_log = float(np.log10(y_val)) if y_val > 0 else -10.0
+                points.append({'x': x_val, 'y': y_log})
             return points
         except Exception as e:
             console.debug(f'Error getting sample data points for model {model_index}: {e}')
@@ -324,12 +516,19 @@ def getExperimentDataPoints(self, experiment_index: int) -> list:
             points = []
             for point in data.data_points():
                 if point[0] < self._project_lib.q_max and self._project_lib.q_min < point[0]:
+                    q = point[0]
+                    r = point[1]
+                    error_var = point[2]
+                    error_lower_linear = max(r - np.sqrt(error_var), 1e-10)
+                    r_val = self._apply_rq4(q, r)
+                    error_upper = self._apply_rq4(q, r + np.sqrt(error_var))
+                    error_lower = self._apply_rq4(q, error_lower_linear)
                     points.append(
                         {
-                            'x': float(point[0]),
-                            'y': float(np.log10(point[1])),
-                            'errorUpper': float(np.log10(point[1] + np.sqrt(point[2]))),
-                            'errorLower': float(np.log10(max(point[1] - np.sqrt(point[2]), 1e-10))),  # Avoid log(0)
+                            'x': float(q),
+                            'y': float(np.log10(r_val)),
+                            'errorUpper': float(np.log10(error_upper)),
+                            'errorLower': float(np.log10(error_lower)),
                         }
                     )
             return points
@@ -347,12 +546,17 @@ def getAnalysisDataPoints(self, experiment_index: int) -> list:
             # Get the model index for this experiment - it may be different from experiment_index
             # When multiple experiments share the same model
             model_index = 0
+            model_found = False
             if hasattr(exp_data, 'model') and exp_data.model is not None:
                 # Find the model index in the models collection
                 for idx, model in enumerate(self._project_lib.models):
                     if model is exp_data.model:
                         model_index = idx
+                        model_found = True
                         break
+                if not model_found:
+                    console.debug(f'Warning: model for experiment {experiment_index} '
+                                  f'not found in models collection, falling back to model 0')
             else:
                 # Fallback: use experiment_index if it's within model range, else 0
                 model_index = experiment_index if experiment_index < len(self._project_lib.models) else 0
@@ -364,20 +568,29 @@ def getAnalysisDataPoints(self, experiment_index: int) -> list:
             q_filtered = q_values[mask]
 
             # Get calculated model data at the same q points using the correct model index
-            calc_data = self._project_lib.sample_data_for_model_at_index(model_index, q_filtered)
+            calc_data = self._project_lib.model_data_for_model_at_index(model_index, q_filtered)
 
             points = []
             exp_points = list(exp_data.data_points())
             calc_y = calc_data.y
 
+            if len(calc_y) != len(q_filtered):
+                console.debug(f'Warning: calculated data length ({len(calc_y)}) '
+                              f'differs from filtered experimental data ({len(q_filtered)}) '
+                              f'for experiment {experiment_index}')
+
             calc_idx = 0
             for point in exp_points:
                 if point[0] < self._project_lib.q_max and self._project_lib.q_min < point[0]:
-                    calc_y_val = calc_y[calc_idx] if calc_idx < len(calc_y) else point[1]
+                    q = point[0]
+                    r_meas = point[1]
+                    calc_y_val = calc_y[calc_idx] if calc_idx < len(calc_y) else r_meas
+                    r_meas = self._apply_rq4(q, r_meas)
+                    calc_y_val = self._apply_rq4(q, calc_y_val)
                     points.append(
                         {
-                            'x': float(point[0]),
-                            'measured': float(np.log10(point[1])),
+                            'x': float(q),
+                            'measured': float(np.log10(r_meas)),
                             'calculated': float(np.log10(calc_y_val)),
                         }
                     )
@@ -390,6 +603,7 @@ def getAnalysisDataPoints(self, experiment_index: int) -> list:
     def refreshSamplePage(self):
         # Clear cached data so it gets recalculated
         self._sample_data = {}
+        self._model_data = {}
         self._sld_data = {}
         # Emit signals to update ranges and trigger QML refresh
         self.sampleChartRangesChanged.emit()
@@ -400,6 +614,7 @@ def refreshExperimentPage(self):
         self.drawMeasuredOnExperimentChart()
 
     def refreshAnalysisPage(self):
+        self._model_data = {}
         self.drawCalculatedAndMeasuredOnAnalysisChart()
 
     def refreshExperimentRanges(self):
@@ -446,6 +661,7 @@ def qtchartsReplaceCalculatedOnSldChartAndRedraw(self):
                 nr_points = nr_points + 1
             console.debug(IO.formatMsg('sub', 'Sld curve', f'{nr_points} points', 'on analysis page', 'replaced'))
 
+    @Slot()
     def drawMeasuredOnExperimentChart(self):
         if PLOT_BACKEND == 'QtCharts':
             if self.is_multi_experiment_mode:
@@ -463,9 +679,16 @@ def qtchartsReplaceMeasuredOnExperimentChartAndRedraw(self):
         nr_points = 0
         for point in self.experiment_data.data_points():
             if point[0] < self._project_lib.q_max and self._project_lib.q_min < point[0]:
-                series_measured.append(point[0], np.log10(point[1]))
-                series_error_upper.append(point[0], np.log10(point[1] + np.sqrt(point[2])))
-                series_error_lower.append(point[0], np.log10(max(point[1] - np.sqrt(point[2]), 1e-10)))
+                q = point[0]
+                r = point[1]
+                error_var = point[2]
+                error_lower_linear = max(r - np.sqrt(error_var), 1e-10)
+                r_val = self._apply_rq4(q, r)
+                error_upper = self._apply_rq4(q, r + np.sqrt(error_var))
+                error_lower = self._apply_rq4(q, error_lower_linear)
+                series_measured.append(q, np.log10(r_val))
+                series_error_upper.append(q, np.log10(error_upper))
+                series_error_lower.append(q, np.log10(error_lower))
                 nr_points = nr_points + 1
 
         console.debug(IO.formatMsg('sub', 'Measured curve', f'{nr_points} points', 'on experiment page', 'replaced'))
@@ -486,6 +709,7 @@ def qtchartsReplaceMultiExperimentChartAndRedraw(self):
         # This method is called to trigger the refresh, actual drawing is handled by QML
         self.experimentDataChanged.emit()
 
+    @Slot()
     def drawCalculatedAndMeasuredOnAnalysisChart(self):
         if PLOT_BACKEND == 'QtCharts':
             if self.is_multi_experiment_mode:
@@ -515,11 +739,15 @@ def qtchartsReplaceCalculatedAndMeasuredOnAnalysisChartAndRedraw(self):
         nr_points = 0
         for point in self.experiment_data.data_points():
             if point[0] < self._project_lib.q_max and self._project_lib.q_min < point[0]:
-                series_measured.append(point[0], np.log10(point[1]))
+                q = point[0]
+                r_meas = self._apply_rq4(q, point[1])
+                series_measured.append(q, np.log10(r_meas))
                 nr_points = nr_points + 1
-        console.debug(IO.formatMsg('sub', 'Measurede curve', f'{nr_points} points', 'on analysis page', 'replaced'))
+        console.debug(IO.formatMsg('sub', 'Measured curve', f'{nr_points} points', 'on analysis page', 'replaced'))
 
-        for point in self.sample_data.data_points():
-            series_calculated.append(point[0], np.log10(point[1]))
+        for point in self.model_data.data_points():
+            q = point[0]
+            r_calc = self._apply_rq4(q, point[1])
+            series_calculated.append(q, np.log10(r_calc))
             nr_points = nr_points + 1
         console.debug(IO.formatMsg('sub', 'Calculated curve', f'{nr_points} points', 'on analysis page', 'replaced'))
diff --git a/EasyReflectometryApp/Backends/Py/project.py b/EasyReflectometryApp/Backends/Py/project.py
index 5217c0df..4fba7149 100644
--- a/EasyReflectometryApp/Backends/Py/project.py
+++ b/EasyReflectometryApp/Backends/Py/project.py
@@ -1,3 +1,5 @@
+import warnings
+
 from EasyApp.Logic.Utils.Utils import generalizePath
 from easyreflectometry import Project as ProjectLib
 from easyreflectometry.orso_utils import load_orso_model
@@ -20,6 +22,7 @@ class Project(QObject):
     externalNameChanged = Signal()
     externalProjectLoaded = Signal()
     externalProjectReset = Signal()
+    sampleLoadWarning = Signal(str)
 
     def __init__(self, project_lib: ProjectLib, parent=None):
         super().__init__(parent)
@@ -104,13 +107,25 @@ def reset(self) -> None:
         self.externalNameChanged.emit()
         self.externalProjectReset.emit()
 
-    @Slot(str)
-    def sampleLoad(self, url: str) -> None:
+    @Slot(str, bool)
+    def sampleLoad(self, url: str, append: bool = True) -> None:
         # Load ORSO file content
         orso_data = orso.load_orso(generalizePath(url))
         # Load the sample model
-        sample = load_orso_model(orso_data)
-        # Add the sample as a new model in the project
-        self._logic.add_sample_from_orso(sample)
+        with warnings.catch_warnings(record=True) as caught_warnings:
+            warnings.simplefilter('always')
+            sample = load_orso_model(orso_data)
+        if sample is None:
+            warning_msg = 'The ORSO file does not contain a valid sample model definition. No sample was loaded.'
+            for w in caught_warnings:
+                warning_msg = str(w.message)
+            self.sampleLoadWarning.emit(warning_msg)
+            return
+        if append:
+            # Add the sample as a new model in the project
+            self._logic.add_sample_from_orso(sample)
+        else:
+            # Replace all existing models with the loaded sample
+            self._logic.replace_models_from_orso(sample)
         # notify listeners
         self.externalProjectLoaded.emit()
diff --git a/EasyReflectometryApp/Backends/Py/py_backend.py b/EasyReflectometryApp/Backends/Py/py_backend.py
index ce924fe8..57ba5a8b 100644
--- a/EasyReflectometryApp/Backends/Py/py_backend.py
+++ b/EasyReflectometryApp/Backends/Py/py_backend.py
@@ -1,4 +1,5 @@
 from EasyApp.Logic.Logging import LoggerLevelHandler
+from EasyApp.Logic.Logging import console
 from easyreflectometry import Project as ProjectLib
 from PySide6.QtCore import Property
 from PySide6.QtCore import QObject
@@ -38,6 +39,9 @@ def __init__(self, parent=None):
 
         self._logger = LoggerLevelHandler(self)
 
+        # Wire cross-cutting references before connecting signals
+        self._status._status_logic.set_minimizers_logic(self._analysis._minimizers_logic)
+
         # Must be last to ensure all backend parts are created
         self._connect_backend_parts()
 
@@ -94,18 +98,18 @@ def analysisSelectedExperimentIndices(self) -> list:
     @Slot('QVariantList')
     def analysisSetSelectedExperimentIndices(self, indices) -> None:
         """Set multiple selected experiment indices."""
-        print(f'PyBackend.analysisSetSelectedExperimentIndices called with: {indices}')
-        print(f'Type of indices: {type(indices)}')
+        console.debug(f'PyBackend.analysisSetSelectedExperimentIndices called with: {indices}')
+        console.debug(f'Type of indices: {type(indices)}')
 
         # Convert QVariantList to Python list if needed
         python_indices = list(indices) if hasattr(indices, '__iter__') else []
-        print(f'Converted to Python list: {python_indices}')
+        console.debug(f'Converted to Python list: {python_indices}')
 
         if hasattr(self._analysis, 'setSelectedExperimentIndices'):
             self._analysis.setSelectedExperimentIndices(python_indices)
-            print('Successfully called analysis.setSelectedExperimentIndices')
+            console.debug('Successfully called analysis.setSelectedExperimentIndices')
         else:
-            print('ERROR: analysis.setSelectedExperimentIndices method not found')
+            console.debug('ERROR: analysis.setSelectedExperimentIndices method not found')
 
         # Emit our local signal to notify QML properties
         self.multiExperimentSelectionChanged.emit()
@@ -177,10 +181,15 @@ def _relay_project_page_created(self):
         self._summary.summaryChanged.emit()
 
     def _relay_project_page_project_changed(self):
+        # Clear layers cache first so that subsequent signal handlers
+        # (e.g. ComboBox onModelChanged / onCurrentAssemblyNameChanged in
+        # MultiLayer.qml) read up-to-date layer data.
+        self._sample._clearCacheAndEmitLayersChanged()
         self._sample.materialsTableChanged.emit()
         self._sample.modelsTableChanged.emit()
+        self._sample.modelsIndexChanged.emit()
         self._sample.assembliesTableChanged.emit()
-        self._sample._clearCacheAndEmitLayersChanged()
+        self._sample.assembliesIndexChanged.emit()
         self._experiment.experimentChanged.emit()
         self._analysis.experimentsChanged.emit()
         self._analysis._clearCacheAndEmitParametersChanged()
@@ -188,12 +197,14 @@ def _relay_project_page_project_changed(self):
         self._summary.summaryChanged.emit()
         self._plotting_1d.reset_data()
         self._refresh_plots()
+        self._plotting_1d.samplePageResetAxes.emit()
 
     def _relay_sample_page_sample_changed(self):
         self._plotting_1d.reset_data()
         self._analysis._clearCacheAndEmitParametersChanged()
         self._status.statusChanged.emit()
         self._summary.summaryChanged.emit()
+        self._plotting_1d.samplePageResetAxes.emit()
 
     def _relay_experiment_page_experiment_changed(self):
         self._analysis.experimentsChanged.emit()
@@ -206,6 +217,7 @@ def _relay_analysis_page(self):
         self._status.statusChanged.emit()
         self._experiment.experimentChanged.emit()
         self._summary.summaryChanged.emit()
+        self._plotting_1d.samplePageResetAxes.emit()
 
     def _refresh_plots(self):
         self._plotting_1d.sampleChartRangesChanged.emit()
diff --git a/EasyReflectometryApp/Backends/Py/sample.py b/EasyReflectometryApp/Backends/Py/sample.py
index 73c7647a..1c73c226 100644
--- a/EasyReflectometryApp/Backends/Py/sample.py
+++ b/EasyReflectometryApp/Backends/Py/sample.py
@@ -552,13 +552,29 @@ def _sanitize_relation(operator: str) -> str:
     def _format_numeric(value: float) -> str:
         return f'{value:.6g}'
 
+    def _get_independent_parameter_entries(self) -> list[dict]:
+        """Return the filtered list of independent+enabled parameter entries.
+
+        This must match the same filtering as dependentParameterNames so that
+        the QML dropdown index maps to the correct parameter object.
+        """
+        entries = []
+        for parameter in self._parameters_logic.parameters:
+            if not parameter['independent']:
+                continue
+            if hasattr(parameter['object'], 'enabled') and not parameter['object'].enabled:
+                continue
+            entries.append(parameter)
+        return entries
+
     def _prepare_constraint_instruction(
         self,
         dependent_index: int,
         relation_operator: str,
         expression: str,
     ) -> dict[str, Any]:
-        if dependent_index < 0 or dependent_index >= len(self._project_lib.parameters):
+        independent_entries = self._get_independent_parameter_entries()
+        if dependent_index < 0 or dependent_index >= len(independent_entries):
             raise ValueError('Select a dependent parameter before defining a constraint.')
 
         relation = self._sanitize_relation(relation_operator)
@@ -868,7 +884,7 @@ def addConstraint(self, dependent_index: int, relation: str, expression: str):
         except Exception as error:  # noqa: BLE001
             return {'success': False, 'message': str(error)}
 
-        dependent = self._project_lib.parameters[dependent_index]
+        dependent = self._get_independent_parameter_entries()[dependent_index]['object']
         previous_state = self._capture_parameter_state(dependent)
         self._ensure_parameter_independent(dependent)
 
diff --git a/EasyReflectometryApp/Gui/Globals/BackendWrapper.qml b/EasyReflectometryApp/Gui/Globals/BackendWrapper.qml
index 15e23f18..df602135 100644
--- a/EasyReflectometryApp/Gui/Globals/BackendWrapper.qml
+++ b/EasyReflectometryApp/Gui/Globals/BackendWrapper.qml
@@ -78,7 +78,17 @@ QtObject {
     function projectReset() { activeBackend.project.reset() }
     function projectSave() { activeBackend.project.save() }
     function projectLoad(value) { activeBackend.project.load(value) }
-    function sampleFileLoad(value) { activeBackend.project.sampleLoad(value) }
+    function sampleFileLoad(value, append) { activeBackend.project.sampleLoad(value, append) }
+
+    // Sample load warning signal - forwarded from backend
+    signal sampleLoadWarning(string message)
+
+    property var _sampleLoadWarningConnection: {
+        if (activeBackend && activeBackend.project && activeBackend.project.sampleLoadWarning) {
+            activeBackend.project.sampleLoadWarning.connect(sampleLoadWarning)
+        }
+        return null
+    }
 
 
     ///////////////
@@ -208,6 +218,7 @@ QtObject {
         try {
             return activeBackend.analysisExperimentsSelectedCount || 1
         } catch (e) {
+            console.warn("analysisExperimentsSelectedCount failed:", e)
             return 1
         }
     }
@@ -215,6 +226,7 @@ QtObject {
         try {
             return activeBackend.analysisSelectedExperimentIndices || []
         } catch (e) {
+            console.warn("analysisSelectedExperimentIndices failed:", e)
             return []
         }
     }
@@ -328,9 +340,84 @@ QtObject {
     readonly property var plottingAnalysisMaxY: activeBackend.plotting.sampleMaxY
     readonly property var calcSerieColor: activeBackend.plotting.calcSerieColor
 
+    // Plot mode properties
+    readonly property bool plottingPlotRQ4: activeBackend.plotting.plotRQ4
+    readonly property string plottingYAxisTitle: activeBackend.plotting.yMainAxisTitle
+    readonly property bool plottingXAxisLog: activeBackend.plotting.xAxisLog
+    readonly property string plottingXAxisType: activeBackend.plotting.xAxisType
+    readonly property bool plottingSldXReversed: activeBackend.plotting.sldXDataReversed
+
+    // Reference line visibility
+    readonly property bool plottingScaleShown: activeBackend.plotting.scaleShown
+    readonly property bool plottingBkgShown: activeBackend.plotting.bkgShown
+
+    // Plot mode toggle functions
+    function plottingTogglePlotRQ4() { activeBackend.plotting.togglePlotRQ4() }
+    function plottingToggleXAxisType() { activeBackend.plotting.toggleXAxisType() }
+    function plottingReverseSldXData() { activeBackend.plotting.reverseSldXData() }
+    function plottingFlipScaleShown() { activeBackend.plotting.flipScaleShown() }
+    function plottingFlipBkgShown() { activeBackend.plotting.flipBkgShown() }
+
+    // Reference line data accessors
+    function plottingGetBackgroundData() {
+        try {
+            return activeBackend.plotting.getBackgroundData()
+        } catch (e) {
+            console.warn("plottingGetBackgroundData failed:", e)
+            return []
+        }
+    }
+    function plottingGetScaleData() {
+        try {
+            return activeBackend.plotting.getScaleData()
+        } catch (e) {
+            console.warn("plottingGetScaleData failed:", e)
+            return []
+        }
+    }
+
+    // Analysis-specific reference line data accessors (use sample/calculated x-range)
+    function plottingGetBackgroundDataForAnalysis() {
+        try {
+            return activeBackend.plotting.getBackgroundDataForAnalysis()
+        } catch (e) {
+            console.warn("plottingGetBackgroundDataForAnalysis failed:", e)
+            return []
+        }
+    }
+    function plottingGetScaleDataForAnalysis() {
+        try {
+            return activeBackend.plotting.getScaleDataForAnalysis()
+        } catch (e) {
+            console.warn("plottingGetScaleDataForAnalysis failed:", e)
+            return []
+        }
+    }
+
+    // Helper to update background/scale reference line series on any chart view.
+    // useAnalysisRange: true for Analysis charts (sample x-range), false for Experiment charts.
+    function updateRefLines(bkgSeries, scaleSeries, useAnalysisRange) {
+        bkgSeries.clear()
+        if (plottingBkgShown) {
+            var bkgData = useAnalysisRange ? plottingGetBackgroundDataForAnalysis() : plottingGetBackgroundData()
+            for (var i = 0; i < bkgData.length; i++) {
+                bkgSeries.append(bkgData[i].x, bkgData[i].y)
+            }
+        }
+        scaleSeries.clear()
+        if (plottingScaleShown) {
+            var scaleData = useAnalysisRange ? plottingGetScaleDataForAnalysis() : plottingGetScaleData()
+            for (var j = 0; j < scaleData.length; j++) {
+                scaleSeries.append(scaleData[j].x, scaleData[j].y)
+            }
+        }
+    }
+
     function plottingSetQtChartsSerieRef(value1, value2, value3) { activeBackend.plotting.setQtChartsSerieRef(value1, value2, value3) }
     function plottingRefreshSample() { activeBackend.plotting.drawCalculatedOnSampleChart() }
     function plottingRefreshSLD() { activeBackend.plotting.drawCalculatedOnSldChart() }
+    function plottingRefreshExperiment() { activeBackend.plotting.drawMeasuredOnExperimentChart() }
+    function plottingRefreshAnalysis() { activeBackend.plotting.drawCalculatedAndMeasuredOnAnalysisChart() }
 
     // Multi-model sample page plotting support
     readonly property int plottingModelCount: activeBackend.plotting.modelCount
@@ -338,6 +425,7 @@ QtObject {
         try {
             return activeBackend.plotting.getSampleDataPointsForModel(index)
         } catch (e) {
+            console.warn("plottingGetSampleDataPointsForModel failed:", e)
             return []
         }
     }
@@ -345,6 +433,7 @@ QtObject {
         try {
             return activeBackend.plotting.getSldDataPointsForModel(index)
         } catch (e) {
+            console.warn("plottingGetSldDataPointsForModel failed:", e)
             return []
         }
     }
@@ -352,18 +441,34 @@ QtObject {
         try {
             return activeBackend.plotting.getModelColor(index)
         } catch (e) {
+            console.warn("plottingGetModelColor failed:", e)
             return '#000000'
         }
     }
 
     // Signal for sample page data changes - forward from backend
     signal samplePageDataChanged()
+    // Signal for resetting chart axes after data load
+    signal samplePageResetAxes()
+    // Signal for plot mode changes - forward from backend
+    signal plotModeChanged()
+    // Signal to request QML to reset chart axes (e.g., after model load)
+    signal chartAxesResetRequested()
 
     // Connect to backend signal (called from Component.onCompleted in QML items)
     function connectSamplePageDataChanged() {
         if (activeBackend && activeBackend.plotting && activeBackend.plotting.samplePageDataChanged) {
             activeBackend.plotting.samplePageDataChanged.connect(samplePageDataChanged)
         }
+        if (activeBackend && activeBackend.plotting && activeBackend.plotting.samplePageResetAxes) {
+            activeBackend.plotting.samplePageResetAxes.connect(samplePageResetAxes)
+        }
+        if (activeBackend && activeBackend.plotting && activeBackend.plotting.plotModeChanged) {
+            activeBackend.plotting.plotModeChanged.connect(plotModeChanged)
+        }
+        if (activeBackend && activeBackend.plotting && activeBackend.plotting.chartAxesResetRequested) {
+            activeBackend.plotting.chartAxesResetRequested.connect(chartAxesResetRequested)
+        }
     }
 
     Component.onCompleted: {
@@ -375,6 +480,7 @@ QtObject {
         try {
             return activeBackend.plottingIsMultiExperimentMode || false
         } catch (e) {
+            console.warn("plottingIsMultiExperimentMode failed:", e)
             return false
         }
     }
@@ -382,6 +488,7 @@ QtObject {
         try {
             return activeBackend.plottingIndividualExperimentDataList || []
         } catch (e) {
+            console.warn("plottingIndividualExperimentDataList failed:", e)
             return []
         }
     }
@@ -389,6 +496,7 @@ QtObject {
         try {
             return activeBackend.plottingGetExperimentDataPoints(index)
         } catch (e) {
+            console.warn("plottingGetExperimentDataPoints failed:", e)
             return []
         }
     }
@@ -396,6 +504,7 @@ QtObject {
         try {
             return activeBackend.plottingGetAnalysisDataPoints(index)
         } catch (e) {
+            console.warn("plottingGetAnalysisDataPoints failed:", e)
             return []
         }
     }
diff --git a/EasyReflectometryApp/Gui/Pages/Analysis/MainContent/AnalysisView.qml b/EasyReflectometryApp/Gui/Pages/Analysis/MainContent/AnalysisView.qml
index 0baf81cd..fec58f95 100644
--- a/EasyReflectometryApp/Gui/Pages/Analysis/MainContent/AnalysisView.qml
+++ b/EasyReflectometryApp/Gui/Pages/Analysis/MainContent/AnalysisView.qml
@@ -31,6 +31,43 @@ Rectangle {
 
         useOpenGL: EaGlobals.Vars.useOpenGL
 
+        // Background reference line series
+        LineSeries {
+            id: backgroundRefLine
+            axisX: chartView.axisX
+            axisY: chartView.axisY
+            useOpenGL: chartView.useOpenGL
+            color: "#888888"
+            width: 1
+            style: Qt.DashLine
+            visible: Globals.BackendWrapper.plottingBkgShown
+        }
+
+        // Scale reference line series
+        LineSeries {
+            id: scaleRefLine
+            axisX: chartView.axisX
+            axisY: chartView.axisY
+            useOpenGL: chartView.useOpenGL
+            color: "#666666"
+            width: 1
+            style: Qt.DotLine
+            visible: Globals.BackendWrapper.plottingScaleShown
+        }
+
+        // Update reference lines when visibility changes
+        Connections {
+            target: Globals.BackendWrapper.activeBackend?.plotting ?? null
+            enabled: target !== null
+            function onReferenceLineVisibilityChanged() {
+                chartView.updateReferenceLines()
+            }
+        }
+
+        function updateReferenceLines() {
+            Globals.BackendWrapper.updateRefLines(backgroundRefLine, scaleRefLine, true)
+        }
+
         // Multi-experiment support
         property var multiExperimentSeries: []
         property bool isMultiExperimentMode: {
@@ -49,12 +86,38 @@ Rectangle {
 
         // Watch for changes in multi-experiment selection
         Connections {
-            target: Globals.BackendWrapper.activeBackend
+            target: Globals.BackendWrapper.activeBackend ?? null
+            enabled: target !== null
             function onMultiExperimentSelectionChanged() {
                 console.log("Analysis: Multi-experiment selection changed - updating series")
                 chartView.updateMultiExperimentSeries()
             }
         }
+
+        // Watch for plot mode changes (R(q)×q⁴ toggle)
+        Connections {
+            target: Globals.BackendWrapper
+            function onPlotModeChanged() {
+                console.debug("AnalysisView: Plot mode changed, refreshing chart")
+                Globals.BackendWrapper.plottingRefreshAnalysis()
+                // Delay resetAxes to allow axis range properties to update first
+                analysisResetAxesTimer.start()
+            }
+            function onChartAxesResetRequested() {
+                // Reset axes when model is loaded (e.g., from ORSO file)
+                analysisResetAxesTimer.start()
+            }
+            function onSamplePageResetAxes() {
+                analysisResetAxesTimer.start()
+            }
+        }
+
+        Timer {
+            id: analysisResetAxesTimer
+            interval: 75
+            repeat: false
+            onTriggered: chartView.resetAxes()
+        }
         
         property double xRange: Globals.BackendWrapper.plottingAnalysisMaxX - Globals.BackendWrapper.plottingAnalysisMinX
         axisX.title: "q (Å⁻¹)"
@@ -64,7 +127,7 @@ Rectangle {
         axisX.maxAfterReset: Globals.BackendWrapper.plottingAnalysisMaxX + xRange * 0.01
 
         property double yRange: Globals.BackendWrapper.plottingAnalysisMaxY - Globals.BackendWrapper.plottingAnalysisMinY
-        axisY.title: "Log10 R(q)"
+        axisY.title: "Log10 " + Globals.BackendWrapper.plottingYAxisTitle
         axisY.min: Globals.BackendWrapper.plottingAnalysisMinY - yRange * 0.01
         axisY.max: Globals.BackendWrapper.plottingAnalysisMaxY + yRange * 0.01
         axisY.minAfterReset: Globals.BackendWrapper.plottingAnalysisMinY - yRange * 0.01
@@ -364,6 +427,9 @@ Rectangle {
 
             // Initialize multi-experiment support
             updateMultiExperimentSeries()
+            
+            // Initialize reference lines
+            updateReferenceLines()
         }
 
         // Update series when chart becomes visible
@@ -371,6 +437,9 @@ Rectangle {
             if (visible && isMultiExperimentMode) {
                 updateMultiExperimentSeries()
             }
+            if (visible) {
+                updateReferenceLines()
+            }
         }
     }
 
diff --git a/EasyReflectometryApp/Gui/Pages/Analysis/MainContent/CombinedView.qml b/EasyReflectometryApp/Gui/Pages/Analysis/MainContent/CombinedView.qml
index 305fe01c..9eab767e 100644
--- a/EasyReflectometryApp/Gui/Pages/Analysis/MainContent/CombinedView.qml
+++ b/EasyReflectometryApp/Gui/Pages/Analysis/MainContent/CombinedView.qml
@@ -12,6 +12,7 @@ import EasyApp.Gui.Globals as EaGlobals
 import EasyApp.Gui.Elements as EaElements
 import EasyApp.Gui.Charts as EaCharts
 
+import Gui as Gui
 import Gui.Globals as Globals
 
 
@@ -63,12 +64,78 @@ Rectangle {
 
                 // Watch for changes in multi-experiment selection
                 Connections {
-                    target: Globals.BackendWrapper.activeBackend
+                    target: Globals.BackendWrapper.activeBackend ?? null
+                    enabled: target !== null
                     function onMultiExperimentSelectionChanged() {
                         analysisChartView.updateMultiExperimentSeries()
                     }
                 }
 
+                // Watch for plot mode changes (R(q)×q⁴ toggle)
+                Connections {
+                    target: Globals.BackendWrapper
+                    function onPlotModeChanged() {
+                        console.debug("CombinedView Analysis: Plot mode changed, refreshing chart")
+                        Globals.BackendWrapper.plottingRefreshAnalysis()
+                        // Delay resetAxes to allow axis range properties to update first
+                        combinedAnalysisResetAxesTimer.start()
+                    }
+                    function onChartAxesResetRequested() {
+                        // Reset axes when model is loaded (e.g., from ORSO file)
+                        combinedAnalysisResetAxesTimer.start()
+                    }
+                    function onSamplePageResetAxes() {
+                        combinedAnalysisResetAxesTimer.start()
+                    }
+                }
+
+                Timer {
+                    id: combinedAnalysisResetAxesTimer
+                    interval: 75
+                    repeat: false
+                    onTriggered: {
+                        analysisChartView.resetAxes()
+                        sldChart.chartView.resetAxes()
+                    }
+                }
+
+                // Background reference line series
+                LineSeries {
+                    id: backgroundRefLine
+                    axisX: analysisChartView.axisX
+                    axisY: analysisChartView.axisY
+                    useOpenGL: analysisChartView.useOpenGL
+                    color: "#888888"
+                    width: 1
+                    style: Qt.DashLine
+                    visible: Globals.BackendWrapper.plottingBkgShown
+                }
+
+                // Scale reference line series
+                LineSeries {
+                    id: scaleRefLine
+                    axisX: analysisChartView.axisX
+                    axisY: analysisChartView.axisY
+                    useOpenGL: analysisChartView.useOpenGL
+                    color: "#666666"
+                    width: 1
+                    style: Qt.DotLine
+                    visible: Globals.BackendWrapper.plottingScaleShown
+                }
+
+                // Update reference lines when visibility changes
+                Connections {
+                    target: Globals.BackendWrapper.activeBackend?.plotting ?? null
+                    enabled: target !== null
+                    function onReferenceLineVisibilityChanged() {
+                        analysisChartView.updateReferenceLines()
+                    }
+                }
+
+                function updateReferenceLines() {
+                    Globals.BackendWrapper.updateRefLines(backgroundRefLine, scaleRefLine, true)
+                }
+
                 // Multi-experiment series management
                 function updateMultiExperimentSeries() {
                     // Always get the latest value from backend
@@ -183,7 +250,7 @@ Rectangle {
                 axisX.maxAfterReset: Globals.BackendWrapper.plottingAnalysisMaxX + xRange * 0.01
 
                 property double yRange: Globals.BackendWrapper.plottingAnalysisMaxY - Globals.BackendWrapper.plottingAnalysisMinY
-                axisY.title: "Log10 R(q)"
+                axisY.title: "Log10 " + Globals.BackendWrapper.plottingYAxisTitle
                 axisY.min: Globals.BackendWrapper.plottingAnalysisMinY - yRange * 0.01
                 axisY.max: Globals.BackendWrapper.plottingAnalysisMaxY + yRange * 0.01
                 axisY.minAfterReset: Globals.BackendWrapper.plottingAnalysisMinY - yRange * 0.01
@@ -246,7 +313,7 @@ Rectangle {
                         ToolTip.text: qsTr("Enable pan")
                         onClicked: {
                             analysisChartView.allowZoom = !analysisChartView.allowZoom
-                            sldChartView.allowZoom = analysisChartView.allowZoom
+                            sldChart.chartView.allowZoom = analysisChartView.allowZoom
                         }
                     }
 
@@ -260,7 +327,7 @@ Rectangle {
                         ToolTip.text: qsTr("Enable box zoom")
                         onClicked: {
                             analysisChartView.allowZoom = !analysisChartView.allowZoom
-                            sldChartView.allowZoom = analysisChartView.allowZoom
+                            sldChart.chartView.allowZoom = analysisChartView.allowZoom
                         }
                     }
 
@@ -273,7 +340,7 @@ Rectangle {
                         ToolTip.text: qsTr("Reset axes")
                         onClicked: {
                             analysisChartView.resetAxes()
-                            sldChartView.resetAxes()
+                            sldChart.chartView.resetAxes()
                         }
                     }
                 }
@@ -381,92 +448,26 @@ Rectangle {
 
                     // Initialize multi-experiment support
                     updateMultiExperimentSeries()
+                    
+                    // Initialize reference lines
+                    updateReferenceLines()
                 }
             }
         }
 
         // SLD Chart (1/3 height)
-        Rectangle {
-            id: sldContainer
+        Gui.SldChart {
+            id: sldChart
+
             SplitView.fillHeight: true
             SplitView.preferredHeight: parent.height * 0.33
             SplitView.minimumHeight: 80
-            color: EaStyle.Colors.chartBackground
-
-            EaCharts.QtCharts1dMeasVsCalc {
-                id: sldChartView
-
-                anchors.fill: parent
-                anchors.topMargin: EaStyle.Sizes.toolButtonHeight - EaStyle.Sizes.fontPixelSize - 1
-
-                useOpenGL: EaGlobals.Vars.useOpenGL
-
-                property double xRange: Globals.BackendWrapper.plottingSldMaxX - Globals.BackendWrapper.plottingSldMinX
-                axisX.title: "z (Å)"
-                axisX.min: Globals.BackendWrapper.plottingSldMinX - xRange * 0.01
-                axisX.max: Globals.BackendWrapper.plottingSldMaxX + xRange * 0.01
-                axisX.minAfterReset: Globals.BackendWrapper.plottingSldMinX - xRange * 0.01
-                axisX.maxAfterReset: Globals.BackendWrapper.plottingSldMaxX + xRange * 0.01
-
-                property double yRange: Globals.BackendWrapper.plottingSldMaxY - Globals.BackendWrapper.plottingSldMinY
-                axisY.title: "SLD (10⁻⁶Å⁻²)"
-                axisY.min: Globals.BackendWrapper.plottingSldMinY - yRange * 0.01
-                axisY.max: Globals.BackendWrapper.plottingSldMaxY + yRange * 0.01
-                axisY.minAfterReset: Globals.BackendWrapper.plottingSldMinY - yRange * 0.01
-                axisY.maxAfterReset: Globals.BackendWrapper.plottingSldMaxY + yRange * 0.01
-
-                calcSerie.onHovered: (point, state) => showMainTooltip(sldChartView, sldDataToolTip, point, state)
-                calcSerie.color: {
-                    const models = Globals.BackendWrapper.sampleModels
-                    const idx = Globals.BackendWrapper.sampleCurrentModelIndex
-
-                    if (models && idx >= 0 && idx < models.length) {
-                        return models[idx].color
-                    }
-
-                    return undefined
-                }
-
-                // Legend
-                Rectangle {
-                    visible: Globals.Variables.showLegendOnAnalysisPage
 
-                    x: sldChartView.plotArea.x + sldChartView.plotArea.width - width - EaStyle.Sizes.fontPixelSize
-                    y: sldChartView.plotArea.y + EaStyle.Sizes.fontPixelSize
-                    width: childrenRect.width
-                    height: childrenRect.height
-
-                    color: EaStyle.Colors.mainContentBackgroundHalfTransparent
-                    border.color: EaStyle.Colors.chartGridLine
+            showLegend: Globals.Variables.showLegendOnAnalysisPage
+            onShowLegendChanged: Globals.Variables.showLegendOnAnalysisPage = showLegend
 
-                    Column {
-                        leftPadding: EaStyle.Sizes.fontPixelSize
-                        rightPadding: EaStyle.Sizes.fontPixelSize
-                        topPadding: EaStyle.Sizes.fontPixelSize * 0.5
-                        bottomPadding: EaStyle.Sizes.fontPixelSize * 0.5
-
-                        EaElements.Label {
-                            text: '━  SLD'
-                            color: sldChartView.calcSerie.color
-                        }
-                    }
-                }
-
-                EaElements.ToolTip {
-                    id: sldDataToolTip
-
-                    arrowLength: 0
-                    textFormat: Text.RichText
-                }
-
-                // Data is set in python backend (plotting_1d.py)
-                Component.onCompleted: {
-                    Globals.References.pages.analysis.mainContent.sldView = sldChartView
-                    Globals.BackendWrapper.plottingSetQtChartsSerieRef('analysisPage',
-                                                                       'sldSerie',
-                                                                       sldChartView.calcSerie)
-                    Globals.BackendWrapper.plottingRefreshSLD()
-                }
+            Component.onCompleted: {
+                Globals.References.pages.analysis.mainContent.sldView = sldChart.chartView
             }
         }
     }
diff --git a/EasyReflectometryApp/Gui/Pages/Analysis/MainContent/SldView.qml b/EasyReflectometryApp/Gui/Pages/Analysis/MainContent/SldView.qml
index d55ca44a..31399d53 100644
--- a/EasyReflectometryApp/Gui/Pages/Analysis/MainContent/SldView.qml
+++ b/EasyReflectometryApp/Gui/Pages/Analysis/MainContent/SldView.qml
@@ -3,181 +3,20 @@
 // © 2025 Contributors to the EasyReflectometry project <https://github.com/easyscience/EasyReflectometry>
 
 import QtQuick
-import QtQuick.Controls
-import QtCharts
-
-import EasyApp.Gui.Style as EaStyle
-import EasyApp.Gui.Globals as EaGlobals
-import EasyApp.Gui.Elements as EaElements
-import EasyApp.Gui.Charts as EaCharts
 
+import Gui as Gui
 import Gui.Globals as Globals
 
 
-Rectangle {
-    id: container
-
-    color: EaStyle.Colors.chartBackground
-
-    EaCharts.QtCharts1dMeasVsCalc {
-        id: chartView
-
-        anchors.topMargin: EaStyle.Sizes.toolButtonHeight - EaStyle.Sizes.fontPixelSize - 1
-
-        useOpenGL: EaGlobals.Vars.useOpenGL
-
-        property double xRange: Globals.BackendWrapper.plottingSldMaxX - Globals.BackendWrapper.plottingSldMinX
-        axisX.title: "z (Å)"
-        axisX.min: Globals.BackendWrapper.plottingSldMinX - xRange * 0.01
-        axisX.max: Globals.BackendWrapper.plottingSldMaxX + xRange * 0.01
-        axisX.minAfterReset: Globals.BackendWrapper.plottingSldMinX - xRange * 0.01
-        axisX.maxAfterReset: Globals.BackendWrapper.plottingSldMaxX + xRange * 0.01
-
-        property double yRange: Globals.BackendWrapper.plottingSldMaxY - Globals.BackendWrapper.plottingSldMinY
-        axisY.title: "SLD (10⁻⁶Å⁻²)"
-        axisY.min: Globals.BackendWrapper.plottingSldMinY - yRange * 0.01
-        axisY.max: Globals.BackendWrapper.plottingSldMaxY + yRange * 0.01
-        axisY.minAfterReset: Globals.BackendWrapper.plottingSldMinY - yRange * 0.01
-        axisY.maxAfterReset: Globals.BackendWrapper.plottingSldMaxY + yRange * 0.01
-
-        calcSerie.onHovered: (point, state) => showMainTooltip(chartView, point, state)
-        calcSerie.color: {
-            const models = Globals.BackendWrapper.sampleModels
-            const idx = Globals.BackendWrapper.sampleCurrentModelIndex
-
-            if (models && idx >= 0 && idx < models.length) {
-                return models[idx].color
-            }
-
-            return undefined
-        }
-
-
-        // Tool buttons
-        Row {
-            id: toolButtons
-
-            x: chartView.plotArea.x + chartView.plotArea.width - width
-            y: chartView.plotArea.y - height - EaStyle.Sizes.fontPixelSize
-
-            spacing: 0.25 * EaStyle.Sizes.fontPixelSize
-
-            EaElements.TabButton {
-                checked: Globals.Variables.showLegendOnSamplePage
-                autoExclusive: false
-                height: EaStyle.Sizes.toolButtonHeight
-                width: EaStyle.Sizes.toolButtonHeight
-                borderColor: EaStyle.Colors.chartAxis
-                fontIcon: "align-left"
-                ToolTip.text: Globals.Variables.showLegendOnSamplePage ?
-                                  qsTr("Hide legend") :
-                                  qsTr("Show legend")
-                onClicked: Globals.Variables.showLegendOnSamplePage = checked
-            }
+Gui.SldChart {
+    id: sldChart
 
-            EaElements.TabButton {
-                checked: chartView.allowHover
-                autoExclusive: false
-                height: EaStyle.Sizes.toolButtonHeight
-                width: EaStyle.Sizes.toolButtonHeight
-                borderColor: EaStyle.Colors.chartAxis
-                fontIcon: "comment-alt"
-                ToolTip.text: qsTr("Show coordinates tooltip on hover")
-                onClicked: chartView.allowHover = !chartView.allowHover
-            }
-
-            Item { height: 1; width: 0.5 * EaStyle.Sizes.fontPixelSize }  // spacer
-
-            EaElements.TabButton {
-                checked: !chartView.allowZoom
-                autoExclusive: false
-                height: EaStyle.Sizes.toolButtonHeight
-                width: EaStyle.Sizes.toolButtonHeight
-                borderColor: EaStyle.Colors.chartAxis
-                fontIcon: "arrows-alt"
-                ToolTip.text: qsTr("Enable pan")
-                onClicked: chartView.allowZoom = !chartView.allowZoom
-            }
-
-            EaElements.TabButton {
-                checked: chartView.allowZoom
-                autoExclusive: false
-                height: EaStyle.Sizes.toolButtonHeight
-                width: EaStyle.Sizes.toolButtonHeight
-                borderColor: EaStyle.Colors.chartAxis
-                fontIcon: "expand"
-                ToolTip.text: qsTr("Enable box zoom")
-                onClicked: chartView.allowZoom = !chartView.allowZoom
-            }
-
-            EaElements.TabButton {
-                checkable: false
-                height: EaStyle.Sizes.toolButtonHeight
-                width: EaStyle.Sizes.toolButtonHeight
-                borderColor: EaStyle.Colors.chartAxis
-                fontIcon: "backspace"
-                ToolTip.text: qsTr("Reset axes")
-                onClicked: chartView.resetAxes()
-            }
-
-        }
-        // Tool buttons
-
-        // Legend
-        Rectangle {
-            visible: Globals.Variables.showLegendOnExperimentPage
-
-            x: chartView.plotArea.x + chartView.plotArea.width - width - EaStyle.Sizes.fontPixelSize
-            y: chartView.plotArea.y + EaStyle.Sizes.fontPixelSize
-            width: childrenRect.width
-            height: childrenRect.height
-
-            color: EaStyle.Colors.mainContentBackgroundHalfTransparent
-            border.color: EaStyle.Colors.chartGridLine
-
-            Column {
-                leftPadding: EaStyle.Sizes.fontPixelSize
-                rightPadding: EaStyle.Sizes.fontPixelSize
-                topPadding: EaStyle.Sizes.fontPixelSize * 0.5
-                bottomPadding: EaStyle.Sizes.fontPixelSize * 0.5
-
-                EaElements.Label {
-                    text: '━  SLD'
-                    color: chartView.calcSerie.color
-                }
-            }
-        }
-        // Legend
-
-        EaElements.ToolTip {
-            id: dataToolTip
-
-            arrowLength: 0
-            textFormat: Text.RichText
-        }
-
-        // Data is set in python backend (plotting_1d.py)
-        Component.onCompleted: {
-            Globals.References.pages.analysis.mainContent.sldView = chartView
-            Globals.BackendWrapper.plottingSetQtChartsSerieRef('analysisPage',
-                                                               'sldSerie',
-                                                               chartView.calcSerie)
-            Globals.BackendWrapper.plottingRefreshSLD()
-        }
-    }
+    showLegend: Globals.Variables.showLegendOnAnalysisPage
 
-    // Logic
+    onShowLegendChanged: Globals.Variables.showLegendOnAnalysisPage = showLegend
 
-    function showMainTooltip(chart, point, state) {
-        if (!chartView.allowHover) {
-            return
-        }
-        const pos = chart.mapToPosition(Qt.point(point.x, point.y))
-        dataToolTip.x = pos.x
-        dataToolTip.y = pos.y
-        dataToolTip.text = `<p align="left">x: ${point.x.toFixed(3)}<br\>y: ${point.y.toFixed(3)}</p>`
-        dataToolTip.parent = chart
-        dataToolTip.visible = state
+    Component.onCompleted: {
+        Globals.References.pages.analysis.mainContent.sldView = sldChart.chartView
     }
 }
 
diff --git a/EasyReflectometryApp/Gui/Pages/Analysis/Sidebar/Advanced/Groups/PlotControl.qml b/EasyReflectometryApp/Gui/Pages/Analysis/Sidebar/Advanced/Groups/PlotControl.qml
new file mode 100644
index 00000000..34de6956
--- /dev/null
+++ b/EasyReflectometryApp/Gui/Pages/Analysis/Sidebar/Advanced/Groups/PlotControl.qml
@@ -0,0 +1,18 @@
+// SPDX-FileCopyrightText: 2025 EasyReflectometry contributors <support@easyreflectometry.org>
+// SPDX-License-Identifier: BSD-3-Clause
+// © 2025 Contributors to the EasyReflectometry project <https://github.com/easyscience/EasyReflectometry>
+
+import QtQuick
+
+import EasyApp.Gui.Style as EaStyle
+import EasyApp.Gui.Elements as EaElements
+
+import Gui as Gui
+
+EaElements.GroupBox {
+    title: qsTr("Plot control")
+    collapsed: true
+
+    Gui.PlotControlRefLines {}
+}
+
diff --git a/EasyReflectometryApp/Gui/Pages/Analysis/Sidebar/Advanced/Layout.qml b/EasyReflectometryApp/Gui/Pages/Analysis/Sidebar/Advanced/Layout.qml
index 2571f4d9..deeee520 100644
--- a/EasyReflectometryApp/Gui/Pages/Analysis/Sidebar/Advanced/Layout.qml
+++ b/EasyReflectometryApp/Gui/Pages/Analysis/Sidebar/Advanced/Layout.qml
@@ -17,4 +17,6 @@ EaComponents.SideBarColumn {
     Groups.Calculator {}
 
     Groups.Minimizer {}
+
+    Groups.PlotControl {}
 }
diff --git a/EasyReflectometryApp/Gui/Pages/Analysis/Sidebar/Basic/Groups/Fittables.qml b/EasyReflectometryApp/Gui/Pages/Analysis/Sidebar/Basic/Groups/Fittables.qml
index 405e5291..10e39a35 100644
--- a/EasyReflectometryApp/Gui/Pages/Analysis/Sidebar/Basic/Groups/Fittables.qml
+++ b/EasyReflectometryApp/Gui/Pages/Analysis/Sidebar/Basic/Groups/Fittables.qml
@@ -261,7 +261,7 @@ EaElements.GroupBox {
                 }
 
                 EaComponents.TableViewLabel {
-                    text: EaLogic.Utils.toDefaultPrecision(Globals.BackendWrapper.analysisFitableParameters[index].error)
+                    text: formatError(Globals.BackendWrapper.analysisFitableParameters[index].error)
                     color: (Globals.BackendWrapper.analysisFitableParameters[index].independent !== undefined ?
                            Globals.BackendWrapper.analysisFitableParameters[index].independent : true) ?
                            EaStyle.Colors.themeForeground : EaStyle.Colors.themeForegroundDisabled
@@ -436,6 +436,13 @@ EaElements.GroupBox {
         fittables.parameterSlider.to = EaLogic.Utils.toDefaultPrecision(to)
     }
 
+    function formatError(value) {
+        if (value === undefined || value === 0 || isNaN(value)) return ''
+        var s = Number(value.toPrecision(2)).toString()
+        if (s.length <= 6) return s
+        return value.toExponential(1)
+    }
+
     function allFittablesSelected() {
         const params = backend.analysisFitableParameters
         if (!params || !params.length) {
diff --git a/EasyReflectometryApp/Gui/Pages/Experiment/Layout.qml b/EasyReflectometryApp/Gui/Pages/Experiment/Layout.qml
index f56ede8a..7c6f1c87 100644
--- a/EasyReflectometryApp/Gui/Pages/Experiment/Layout.qml
+++ b/EasyReflectometryApp/Gui/Pages/Experiment/Layout.qml
@@ -22,13 +22,13 @@ EaComponents.ContentPage {
 
     sideBar: EaComponents.SideBar {
         tabs: [
-            EaElements.TabButton { text: qsTr('Basic controls') }
-//            EaElements.TabButton { text: qsTr('Advanced controls') }
+            EaElements.TabButton { text: qsTr('Basic controls') },
+            EaElements.TabButton { text: qsTr('Advanced controls') }
         ]
 
         items: [
-            Loader { source: 'Sidebar/Basic/Layout.qml' }
- //           Loader { source: 'Sidebar/Advanced/Layout.qml' }
+            Loader { source: 'Sidebar/Basic/Layout.qml' },
+            Loader { source: 'Sidebar/Advanced/Layout.qml' }
         ]
 
         continueButton.text: qsTr('Continue') 
diff --git a/EasyReflectometryApp/Gui/Pages/Experiment/MainContent/ExperimentView.qml b/EasyReflectometryApp/Gui/Pages/Experiment/MainContent/ExperimentView.qml
index 905dc7c9..070e809d 100644
--- a/EasyReflectometryApp/Gui/Pages/Experiment/MainContent/ExperimentView.qml
+++ b/EasyReflectometryApp/Gui/Pages/Experiment/MainContent/ExperimentView.qml
@@ -32,6 +32,43 @@ Rectangle {
 
         useOpenGL: EaGlobals.Vars.useOpenGL
 
+        // Background reference line series
+        LineSeries {
+            id: backgroundRefLine
+            axisX: chartView.axisX
+            axisY: chartView.axisY
+            useOpenGL: chartView.useOpenGL
+            color: "#888888"
+            width: 1
+            style: Qt.DashLine
+            visible: Globals.BackendWrapper.plottingBkgShown
+        }
+
+        // Scale reference line series
+        LineSeries {
+            id: scaleRefLine
+            axisX: chartView.axisX
+            axisY: chartView.axisY
+            useOpenGL: chartView.useOpenGL
+            color: "#666666"
+            width: 1
+            style: Qt.DotLine
+            visible: Globals.BackendWrapper.plottingScaleShown
+        }
+
+        // Update reference lines when visibility changes
+        Connections {
+            target: Globals.BackendWrapper.activeBackend?.plotting ?? null
+            enabled: target !== null
+            function onReferenceLineVisibilityChanged() {
+                chartView.updateReferenceLines()
+            }
+        }
+
+        function updateReferenceLines() {
+            Globals.BackendWrapper.updateRefLines(backgroundRefLine, scaleRefLine, false)
+        }
+
         // Multi-experiment support
         property var multiExperimentSeries: []
         property bool isMultiExperimentMode: {
@@ -137,7 +174,8 @@ Rectangle {
 
         // Watch for changes in multi-experiment selection
         Connections {
-            target: Globals.BackendWrapper.activeBackend
+            target: Globals.BackendWrapper.activeBackend ?? null
+            enabled: target !== null
             function onMultiExperimentSelectionChanged() {
                 // Update series when selection changes
                 // The function will handle showing/hiding appropriate series
@@ -145,6 +183,28 @@ Rectangle {
                 chartView.updateMultiExperimentSeries()
             }
         }
+
+        // Watch for plot mode changes (R(q)×q⁴ toggle)
+        Connections {
+            target: Globals.BackendWrapper
+            function onPlotModeChanged() {
+                console.debug("ExperimentView: Plot mode changed, refreshing chart")
+                Globals.BackendWrapper.plottingRefreshExperiment()
+                // Delay resetAxes to allow axis range properties to update first
+                experimentResetAxesTimer.start()
+            }
+            function onChartAxesResetRequested() {
+                // Reset axes when model is loaded (e.g., from ORSO file)
+                experimentResetAxesTimer.start()
+            }
+        }
+
+        Timer {
+            id: experimentResetAxesTimer
+            interval: 75
+            repeat: false
+            onTriggered: chartView.resetAxes()
+        }
         
         property double xRange: Globals.BackendWrapper.plottingExperimentMaxX - Globals.BackendWrapper.plottingExperimentMinX
         axisX.title: "q (Å⁻¹)"
@@ -154,7 +214,7 @@ Rectangle {
         axisX.maxAfterReset: Globals.BackendWrapper.plottingExperimentMaxX + xRange * 0.01
 
         property double yRange: Globals.BackendWrapper.plottingExperimentMaxY - Globals.BackendWrapper.plottingExperimentMinY
-        axisY.title: "Log10 R(q)"
+        axisY.title: "Log10 " + Globals.BackendWrapper.plottingYAxisTitle
         axisY.min: Globals.BackendWrapper.plottingExperimentMinY - yRange * 0.01
         axisY.max: Globals.BackendWrapper.plottingExperimentMaxY + yRange * 0.01
         axisY.minAfterReset: Globals.BackendWrapper.plottingExperimentMinY - yRange * 0.01
@@ -491,6 +551,9 @@ Rectangle {
             // Initialize multi-experiment support
             // console.log("ExperimentView initialized - checking multi-experiment mode...")
             updateMultiExperimentSeries()
+
+            // Initialize reference lines
+            updateReferenceLines()
         }
 
         // Update series when chart becomes visible
@@ -498,6 +561,9 @@ Rectangle {
             if (visible && isMultiExperimentMode) {
                 updateMultiExperimentSeries()
             }
+            if (visible) {
+                updateReferenceLines()
+            }
         }
     }
 
diff --git a/EasyReflectometryApp/Gui/Pages/Experiment/Sidebar/Advanced/Groups/PlotControl.qml b/EasyReflectometryApp/Gui/Pages/Experiment/Sidebar/Advanced/Groups/PlotControl.qml
new file mode 100644
index 00000000..ccf27b4d
--- /dev/null
+++ b/EasyReflectometryApp/Gui/Pages/Experiment/Sidebar/Advanced/Groups/PlotControl.qml
@@ -0,0 +1,61 @@
+// SPDX-FileCopyrightText: 2025 EasyReflectometry contributors <support@easyreflectometry.org>
+// SPDX-License-Identifier: BSD-3-Clause
+// © 2025 Contributors to the EasyReflectometry project <https://github.com/easyscience/EasyReflectometry>
+
+import QtQuick
+import QtQuick.Controls
+
+import EasyApp.Gui.Style as EaStyle
+import EasyApp.Gui.Elements as EaElements
+
+import Gui.Globals as Globals
+
+EaElements.GroupBox {
+    title: qsTr("Plot control")
+    collapsed: true
+
+    Column {
+        spacing: EaStyle.Sizes.fontPixelSize * 0.5
+
+        EaElements.CheckBox {
+            topPadding: 0
+            checked: Globals.BackendWrapper.plottingPlotRQ4
+            text: qsTr("Plot R(q)×q⁴")
+            ToolTip.text: qsTr("Checking this box will plot R(q) multiplied by q⁴")
+            onToggled: {
+                Globals.BackendWrapper.plottingTogglePlotRQ4()
+            }
+        }
+
+        EaElements.CheckBox {
+            topPadding: 0
+            checked: Globals.Variables.logarithmicQAxis
+            text: qsTr("Logarithmic q-axis")
+            ToolTip.text: qsTr("Checking this box will make the q-axis logarithmic")
+            onToggled: {
+                Globals.Variables.logarithmicQAxis = checked
+            }
+        }
+
+        EaElements.CheckBox {
+            topPadding: 0
+            checked: Globals.BackendWrapper.plottingScaleShown
+            text: qsTr("Show scale line")
+            ToolTip.text: qsTr("Checking this box will show the scale reference line on the plot")
+            onToggled: {
+                Globals.BackendWrapper.plottingFlipScaleShown()
+            }
+        }
+
+        EaElements.CheckBox {
+            topPadding: 0
+            checked: Globals.BackendWrapper.plottingBkgShown
+            text: qsTr("Show background line")
+            ToolTip.text: qsTr("Checking this box will show the background reference line on the plot")
+            onToggled: {
+                Globals.BackendWrapper.plottingFlipBkgShown()
+            }
+        }
+    }
+}
+
diff --git a/EasyReflectometryApp/Gui/Pages/Experiment/Sidebar/Advanced/Layout.qml b/EasyReflectometryApp/Gui/Pages/Experiment/Sidebar/Advanced/Layout.qml
new file mode 100644
index 00000000..600ca675
--- /dev/null
+++ b/EasyReflectometryApp/Gui/Pages/Experiment/Sidebar/Advanced/Layout.qml
@@ -0,0 +1,17 @@
+// SPDX-FileCopyrightText: 2025 EasyReflectometry contributors <support@easyreflectometry.org>
+// SPDX-License-Identifier: BSD-3-Clause
+// © 2025 Contributors to the EasyReflectometry project <https://github.com/easyscience/EasyReflectometry>
+
+import QtQuick
+
+import EasyApp.Gui.Elements as EaElements
+import EasyApp.Gui.Components as EaComponents
+
+import "./Groups" as Groups
+
+
+EaComponents.SideBarColumn {
+
+    Groups.PlotControl {}
+
+}
diff --git a/EasyReflectometryApp/Gui/Pages/Sample/MainContent/CombinedView.qml b/EasyReflectometryApp/Gui/Pages/Sample/MainContent/CombinedView.qml
index fb2f6d4e..3801d2e6 100644
--- a/EasyReflectometryApp/Gui/Pages/Sample/MainContent/CombinedView.qml
+++ b/EasyReflectometryApp/Gui/Pages/Sample/MainContent/CombinedView.qml
@@ -12,6 +12,7 @@ import EasyApp.Gui.Globals as EaGlobals
 import EasyApp.Gui.Elements as EaElements
 import EasyApp.Gui.Charts as EaCharts
 
+import Gui as Gui
 import Gui.Globals as Globals
 
 
@@ -25,7 +26,6 @@ Rectangle {
 
     // Store dynamically created series
     property var sampleSeries: []
-    property var sldSeries: []
 
     SplitView {
         anchors.fill: parent
@@ -101,7 +101,7 @@ Rectangle {
 
                 ValueAxis {
                     id: sampleAxisY
-                    titleText: "Log10 R(q)"
+                    titleText: "Log10 " + Globals.BackendWrapper.plottingYAxisTitle
                     // min/max set imperatively to avoid binding reset during zoom
                     property double minAfterReset: Globals.BackendWrapper.plottingSampleMinY - sampleChartView.yRange * 0.01
                     property double maxAfterReset: Globals.BackendWrapper.plottingSampleMaxY + sampleChartView.yRange * 0.01
@@ -180,7 +180,7 @@ Rectangle {
                         ToolTip.text: qsTr("Enable pan")
                         onClicked: {
                             sampleChartView.allowZoom = !checked
-                            sldChartView.allowZoom = !checked
+                            sldChart.chartView.allowZoom = !checked
                         }
                     }
 
@@ -194,7 +194,7 @@ Rectangle {
                         ToolTip.text: qsTr("Enable box zoom")
                         onClicked: {
                             sampleChartView.allowZoom = checked
-                            sldChartView.allowZoom = checked
+                            sldChart.chartView.allowZoom = checked
                         }
                     }
 
@@ -207,7 +207,7 @@ Rectangle {
                         ToolTip.text: qsTr("Reset axes")
                         onClicked: {
                             sampleChartView.resetAxes()
-                            sldChartView.resetAxes()
+                            sldChart.chartView.resetAxes()
                         }
                     }
                 }
@@ -360,222 +360,19 @@ Rectangle {
         }
 
         // SLD Chart (1/3 height)
-        Rectangle {
-            id: sldContainer
+        Gui.SldChart {
+            id: sldChart
+
             SplitView.fillHeight: true
             SplitView.preferredHeight: parent.height * 0.33
             SplitView.minimumHeight: 80
-            color: EaStyle.Colors.chartBackground
-
-            ChartView {
-                id: sldChartView
-
-                anchors.fill: parent
-                anchors.topMargin: EaStyle.Sizes.toolButtonHeight - EaStyle.Sizes.fontPixelSize - 1
-                anchors.margins: -12
-
-                antialiasing: true
-                legend.visible: false
-                backgroundRoundness: 0
-                backgroundColor: EaStyle.Colors.chartBackground
-                plotAreaColor: EaStyle.Colors.chartPlotAreaBackground
-
-                property bool allowZoom: true
-                property bool allowHover: true
-
-                property double xRange: Globals.BackendWrapper.plottingSldMaxX - Globals.BackendWrapper.plottingSldMinX
-
-                // Reverse axis logic
-                property bool reverseZAxis: Globals.Variables.reverseSldZAxis
-
-                ValueAxis {
-                    id: sldAxisX
-                    titleText: "z (Å)"
-                    // min/max set imperatively to avoid binding reset during zoom
-                    property double minAfterReset: Globals.BackendWrapper.plottingSldMinX - sldChartView.xRange * 0.01
-                    property double maxAfterReset: Globals.BackendWrapper.plottingSldMaxX + sldChartView.xRange * 0.01
-                    reverse: sldChartView.reverseZAxis
-                    color: EaStyle.Colors.chartAxis
-                    gridLineColor: EaStyle.Colors.chartGridLine
-                    minorGridLineColor: EaStyle.Colors.chartMinorGridLine
-                    labelsColor: EaStyle.Colors.chartLabels
-                    titleBrush: EaStyle.Colors.chartLabels
-                    Component.onCompleted: {
-                        min = minAfterReset
-                        max = maxAfterReset
-                    }
-                }
-
-                property double yRange: Globals.BackendWrapper.plottingSldMaxY - Globals.BackendWrapper.plottingSldMinY
-
-                ValueAxis {
-                    id: sldAxisY
-                    titleText: "SLD (10⁻⁶Å⁻²)"
-                    // min/max set imperatively to avoid binding reset during zoom
-                    property double minAfterReset: Globals.BackendWrapper.plottingSldMinY - sldChartView.yRange * 0.01
-                    property double maxAfterReset: Globals.BackendWrapper.plottingSldMaxY + sldChartView.yRange * 0.01
-                    color: EaStyle.Colors.chartAxis
-                    gridLineColor: EaStyle.Colors.chartGridLine
-                    minorGridLineColor: EaStyle.Colors.chartMinorGridLine
-                    labelsColor: EaStyle.Colors.chartLabels
-                    titleBrush: EaStyle.Colors.chartLabels
-                    Component.onCompleted: {
-                        min = minAfterReset
-                        max = maxAfterReset
-                    }
-                }
-
-                function resetAxes() {
-                    sldAxisX.min = sldAxisX.minAfterReset
-                    sldAxisX.max = sldAxisX.maxAfterReset
-                    sldAxisY.min = sldAxisY.minAfterReset
-                    sldAxisY.max = sldAxisY.maxAfterReset
-                }
-
-                // Legend showing all models
-                Rectangle {
-                    visible: Globals.Variables.showLegendOnSamplePage
-
-                    x: sldChartView.plotArea.x + sldChartView.plotArea.width - width - EaStyle.Sizes.fontPixelSize
-                    y: sldChartView.plotArea.y + EaStyle.Sizes.fontPixelSize
-                    width: childrenRect.width
-                    height: childrenRect.height
-
-                    color: EaStyle.Colors.mainContentBackgroundHalfTransparent
-                    border.color: EaStyle.Colors.chartGridLine
-
-                    Column {
-                        leftPadding: EaStyle.Sizes.fontPixelSize
-                        rightPadding: EaStyle.Sizes.fontPixelSize
-                        topPadding: EaStyle.Sizes.fontPixelSize * 0.5
-                        bottomPadding: EaStyle.Sizes.fontPixelSize * 0.5
-
-                        Repeater {
-                            model: container.modelCount
-                            EaElements.Label {
-                                text: '━  SLD ' + Globals.BackendWrapper.sampleModels[index].label
-                                color: Globals.BackendWrapper.sampleModels[index].color
-                            }
-                        }
-                    }
-                }
-
-                EaElements.ToolTip {
-                    id: sldDataToolTip
-
-                    arrowLength: 0
-                    textFormat: Text.RichText
-                }
-
-                // Zoom rectangle
-                Rectangle {
-                    id: sldRecZoom
-
-                    property int xScaleZoom: 0
-                    property int yScaleZoom: 0
-
-                    visible: false
-                    transform: Scale {
-                        origin.x: 0
-                        origin.y: 0
-                        xScale: sldRecZoom.xScaleZoom
-                        yScale: sldRecZoom.yScaleZoom
-                    }
-                    border.color: EaStyle.Colors.appBorder
-                    border.width: 1
-                    opacity: 0.9
-                    color: "transparent"
-
-                    Rectangle {
-                        anchors.fill: parent
-                        opacity: 0.5
-                        color: sldRecZoom.border.color
-                    }
-                }
-
-                // Zoom with left mouse button
-                MouseArea {
-                    id: sldZoomMouseArea
-
-                    enabled: sldChartView.allowZoom
-                    anchors.fill: sldChartView
-                    acceptedButtons: Qt.LeftButton
-                    onPressed: {
-                        sldRecZoom.x = mouseX
-                        sldRecZoom.y = mouseY
-                        sldRecZoom.visible = true
-                    }
-                    onMouseXChanged: {
-                        if (mouseX > sldRecZoom.x) {
-                            sldRecZoom.xScaleZoom = 1
-                            sldRecZoom.width = Math.min(mouseX, sldChartView.width) - sldRecZoom.x
-                        } else {
-                            sldRecZoom.xScaleZoom = -1
-                            sldRecZoom.width = sldRecZoom.x - Math.max(mouseX, 0)
-                        }
-                    }
-                    onMouseYChanged: {
-                        if (mouseY > sldRecZoom.y) {
-                            sldRecZoom.yScaleZoom = 1
-                            sldRecZoom.height = Math.min(mouseY, sldChartView.height) - sldRecZoom.y
-                        } else {
-                            sldRecZoom.yScaleZoom = -1
-                            sldRecZoom.height = sldRecZoom.y - Math.max(mouseY, 0)
-                        }
-                    }
-                    onReleased: {
-                        const x = Math.min(sldRecZoom.x, mouseX) - sldChartView.anchors.leftMargin
-                        const y = Math.min(sldRecZoom.y, mouseY) - sldChartView.anchors.topMargin
-                        const width = sldRecZoom.width
-                        const height = sldRecZoom.height
-                        sldChartView.zoomIn(Qt.rect(x, y, width, height))
-                        sldRecZoom.visible = false
-                    }
-                }
-
-                // Pan with left mouse button
-                MouseArea {
-                    property real pressedX
-                    property real pressedY
-                    property int threshold: 1
-
-                    enabled: !sldZoomMouseArea.enabled
-                    anchors.fill: sldChartView
-                    acceptedButtons: Qt.LeftButton
-                    onPressed: {
-                        pressedX = mouseX
-                        pressedY = mouseY
-                    }
-                    onMouseXChanged: Qt.callLater(update)
-                    onMouseYChanged: Qt.callLater(update)
-
-                    function update() {
-                        const dx = mouseX - pressedX
-                        const dy = mouseY - pressedY
-                        pressedX = mouseX
-                        pressedY = mouseY
-
-                        if (dx > threshold)
-                            sldChartView.scrollLeft(dx)
-                        else if (dx < -threshold)
-                            sldChartView.scrollRight(-dx)
-                        if (dy > threshold)
-                            sldChartView.scrollUp(dy)
-                        else if (dy < -threshold)
-                            sldChartView.scrollDown(-dy)
-                    }
-                }
 
-                // Reset axes with right mouse button
-                MouseArea {
-                    anchors.fill: sldChartView
-                    acceptedButtons: Qt.RightButton
-                    onClicked: sldChartView.resetAxes()
-                }
+            showLegend: Globals.Variables.showLegendOnSamplePage
+            reverseZAxis: Globals.Variables.reverseSldZAxis
+            onShowLegendChanged: Globals.Variables.showLegendOnSamplePage = showLegend
 
-                Component.onCompleted: {
-                    Globals.References.pages.sample.mainContent.sldView = sldChartView
-                }
+            Component.onCompleted: {
+                Globals.References.pages.sample.mainContent.sldView = sldChart.chartView
             }
         }
     }
@@ -591,6 +388,36 @@ Rectangle {
         function onSamplePageDataChanged() {
             refreshAllCharts()
         }
+        function onSamplePageResetAxes() {
+            sampleCombinedResetAxesTimer.start()
+            sldCombinedResetAxesTimer.start()
+        }
+        function onPlotModeChanged() {
+            refreshAllCharts()
+            // Delay resetAxes to allow axis range properties to update first
+            sampleCombinedResetAxesTimer.start()
+        }
+        function onChartAxesResetRequested() {
+            // Reset axes when model is loaded (e.g., from ORSO file)
+            sampleCombinedResetAxesTimer.start()
+        }
+    }
+
+    Timer {
+        id: sampleCombinedResetAxesTimer
+        interval: 75
+        repeat: false
+        onTriggered: {
+            sampleChartView.resetAxes()
+            sldChart.chartView.resetAxes()
+        }
+    }
+
+    Timer {
+        id: sldCombinedResetAxesTimer
+        interval: 75
+        repeat: false
+        onTriggered: sldChart.chartView.resetAxes()
     }
 
     Component.onCompleted: {
@@ -607,14 +434,6 @@ Rectangle {
         }
         sampleSeries = []
 
-        // Remove old SLD series
-        for (let j = 0; j < sldSeries.length; j++) {
-            if (sldSeries[j]) {
-                sldChartView.removeSeries(sldSeries[j])
-            }
-        }
-        sldSeries = []
-
         // Determine which x-axis to use for sample chart based on log setting
         const sampleXAxisToUse = sampleChartView.useLogQAxis ? sampleAxisXLog : sampleAxisX
 
@@ -629,15 +448,6 @@ Rectangle {
             // Connect hovered signal for tooltip
             sampleLine.hovered.connect((point, state) => showMainTooltip(sampleChartView, sampleDataToolTip, point, state))
             sampleSeries.push(sampleLine)
-
-            // Create SLD series
-            const sldLine = sldChartView.createSeries(ChartView.SeriesTypeLine, "SLD " + models[k].label, sldAxisX, sldAxisY)
-            sldLine.color = models[k].color
-            sldLine.width = 2
-            sldLine.useOpenGL = EaGlobals.Vars.useOpenGL
-            // Connect hovered signal for tooltip
-            sldLine.hovered.connect((point, state) => showMainTooltip(sldChartView, sldDataToolTip, point, state))
-            sldSeries.push(sldLine)
         }
 
         // Populate data
@@ -659,18 +469,6 @@ Rectangle {
                 }
             }
         }
-
-        // Refresh SLD series
-        for (let j = 0; j < sldSeries.length && j < models.length; j++) {
-            const series = sldSeries[j]
-            if (series) {
-                series.clear()
-                const points = Globals.BackendWrapper.plottingGetSldDataPointsForModel(j)
-                for (let p = 0; p < points.length; p++) {
-                    series.append(points[p].x, points[p].y)
-                }
-            }
-        }
     }
 
     // Logic
diff --git a/EasyReflectometryApp/Gui/Pages/Sample/MainContent/SampleView.qml b/EasyReflectometryApp/Gui/Pages/Sample/MainContent/SampleView.qml
index 01645bfa..38c821cd 100644
--- a/EasyReflectometryApp/Gui/Pages/Sample/MainContent/SampleView.qml
+++ b/EasyReflectometryApp/Gui/Pages/Sample/MainContent/SampleView.qml
@@ -87,7 +87,7 @@ Rectangle {
 
         ValueAxis {
             id: axisY
-            titleText: "Log10 R(q)"
+            titleText: "Log10 " + Globals.BackendWrapper.plottingYAxisTitle
             // min/max set imperatively to avoid binding reset during zoom
             property double minAfterReset: Globals.BackendWrapper.plottingSampleMinY - chartView.yRange * 0.01
             property double maxAfterReset: Globals.BackendWrapper.plottingSampleMaxY + chartView.yRange * 0.01
@@ -347,6 +347,25 @@ Rectangle {
         function onSamplePageDataChanged() {
             refreshAllCharts()
         }
+        function onSamplePageResetAxes() {
+            sampleResetAxesTimer.start()
+        }
+        function onPlotModeChanged() {
+            refreshAllCharts()
+            // Delay resetAxes to allow axis range properties to update first
+            sampleResetAxesTimer.start()
+        }
+        function onChartAxesResetRequested() {
+            // Reset axes when model is loaded (e.g., from ORSO file)
+            sampleResetAxesTimer.start()
+        }
+    }
+
+    Timer {
+        id: sampleResetAxesTimer
+        interval: 75
+        repeat: false
+        onTriggered: chartView.resetAxes()
     }
 
     Component.onCompleted: {
diff --git a/EasyReflectometryApp/Gui/Pages/Sample/MainContent/SldView.qml b/EasyReflectometryApp/Gui/Pages/Sample/MainContent/SldView.qml
index e27d98f5..d8e0fe08 100644
--- a/EasyReflectometryApp/Gui/Pages/Sample/MainContent/SldView.qml
+++ b/EasyReflectometryApp/Gui/Pages/Sample/MainContent/SldView.qml
@@ -3,375 +3,21 @@
 // © 2025 Contributors to the EasyReflectometry project <https://github.com/easyscience/EasyReflectometry>
 
 import QtQuick
-import QtQuick.Controls
-import QtCharts
-
-import EasyApp.Gui.Style as EaStyle
-import EasyApp.Gui.Globals as EaGlobals
-import EasyApp.Gui.Elements as EaElements
-import EasyApp.Gui.Charts as EaCharts
 
+import Gui as Gui
 import Gui.Globals as Globals
 
 
-Rectangle {
-    id: container
-
-    color: EaStyle.Colors.chartBackground
-
-    // Track model count changes to refresh charts
-    property int modelCount: Globals.BackendWrapper.sampleModels.length
-
-    // Store dynamically created series
-    property var sldSeries: []
-
-    ChartView {
-        id: chartView
-
-        anchors.fill: parent
-        anchors.topMargin: EaStyle.Sizes.toolButtonHeight - EaStyle.Sizes.fontPixelSize - 1
-        anchors.margins: -12
-
-        antialiasing: true
-        legend.visible: false
-        backgroundRoundness: 0
-        backgroundColor: EaStyle.Colors.chartBackground
-        plotAreaColor: EaStyle.Colors.chartPlotAreaBackground
-
-        property bool allowZoom: true
-        property bool allowHover: true
-
-        property double xRange: Globals.BackendWrapper.plottingSldMaxX - Globals.BackendWrapper.plottingSldMinX
-
-        // Reverse axis logic
-        property bool reverseZAxis: Globals.Variables.reverseSldZAxis
-
-        ValueAxis {
-            id: axisX
-            titleText: "z (Å)"
-            // min/max set imperatively to avoid binding reset during zoom
-            property double minAfterReset: Globals.BackendWrapper.plottingSldMinX - chartView.xRange * 0.01
-            property double maxAfterReset: Globals.BackendWrapper.plottingSldMaxX + chartView.xRange * 0.01
-            reverse: chartView.reverseZAxis
-            color: EaStyle.Colors.chartAxis
-            gridLineColor: EaStyle.Colors.chartGridLine
-            minorGridLineColor: EaStyle.Colors.chartMinorGridLine
-            labelsColor: EaStyle.Colors.chartLabels
-            titleBrush: EaStyle.Colors.chartLabels
-            Component.onCompleted: {
-                min = minAfterReset
-                max = maxAfterReset
-            }
-        }
-
-        property double yRange: Globals.BackendWrapper.plottingSldMaxY - Globals.BackendWrapper.plottingSldMinY
-
-        ValueAxis {
-            id: axisY
-            titleText: "SLD (10⁻⁶ Å⁻²)"
-            // min/max set imperatively to avoid binding reset during zoom
-            property double minAfterReset: Globals.BackendWrapper.plottingSldMinY - chartView.yRange * 0.01
-            property double maxAfterReset: Globals.BackendWrapper.plottingSldMaxY + chartView.yRange * 0.01
-            color: EaStyle.Colors.chartAxis
-            gridLineColor: EaStyle.Colors.chartGridLine
-            minorGridLineColor: EaStyle.Colors.chartMinorGridLine
-            labelsColor: EaStyle.Colors.chartLabels
-            titleBrush: EaStyle.Colors.chartLabels
-            Component.onCompleted: {
-                min = minAfterReset
-                max = maxAfterReset
-            }
-        }
-
-        function resetAxes() {
-            axisX.min = axisX.minAfterReset
-            axisX.max = axisX.maxAfterReset
-            axisY.min = axisY.minAfterReset
-            axisY.max = axisY.maxAfterReset
-        }
-
-        // Tool buttons
-        Row {
-            id: toolButtons
-            z: 1  // Keep buttons above MouseAreas
-
-            x: chartView.plotArea.x + chartView.plotArea.width - width
-            y: chartView.plotArea.y - height - EaStyle.Sizes.fontPixelSize
-
-            spacing: 0.25 * EaStyle.Sizes.fontPixelSize
-
-            EaElements.TabButton {
-                checked: Globals.Variables.showLegendOnSamplePage
-                autoExclusive: false
-                height: EaStyle.Sizes.toolButtonHeight
-                width: EaStyle.Sizes.toolButtonHeight
-                borderColor: EaStyle.Colors.chartAxis
-                fontIcon: "align-left"
-                ToolTip.text: Globals.Variables.showLegendOnSamplePage ?
-                                  qsTr("Hide legend") :
-                                  qsTr("Show legend")
-                onClicked: Globals.Variables.showLegendOnSamplePage = checked
-            }
-
-            EaElements.TabButton {
-                checked: chartView.allowHover
-                autoExclusive: false
-                height: EaStyle.Sizes.toolButtonHeight
-                width: EaStyle.Sizes.toolButtonHeight
-                borderColor: EaStyle.Colors.chartAxis
-                fontIcon: "comment-alt"
-                ToolTip.text: qsTr("Show coordinates tooltip on hover")
-                onClicked: chartView.allowHover = checked
-            }
-
-            Item { height: 1; width: 0.5 * EaStyle.Sizes.fontPixelSize }  // spacer
-
-            EaElements.TabButton {
-                checked: !chartView.allowZoom
-                autoExclusive: false
-                height: EaStyle.Sizes.toolButtonHeight
-                width: EaStyle.Sizes.toolButtonHeight
-                borderColor: EaStyle.Colors.chartAxis
-                fontIcon: "arrows-alt"
-                ToolTip.text: qsTr("Enable pan")
-                onClicked: chartView.allowZoom = !checked
-            }
-
-            EaElements.TabButton {
-                checked: chartView.allowZoom
-                autoExclusive: false
-                height: EaStyle.Sizes.toolButtonHeight
-                width: EaStyle.Sizes.toolButtonHeight
-                borderColor: EaStyle.Colors.chartAxis
-                fontIcon: "expand"
-                ToolTip.text: qsTr("Enable box zoom")
-                onClicked: chartView.allowZoom = checked
-            }
-
-            EaElements.TabButton {
-                checkable: false
-                height: EaStyle.Sizes.toolButtonHeight
-                width: EaStyle.Sizes.toolButtonHeight
-                borderColor: EaStyle.Colors.chartAxis
-                fontIcon: "backspace"
-                ToolTip.text: qsTr("Reset axes")
-                onClicked: chartView.resetAxes()
-            }
-
-        }
-
-        // Legend showing all models
-        Rectangle {
-            visible: Globals.Variables.showLegendOnSamplePage
-
-            x: chartView.plotArea.x + chartView.plotArea.width - width - EaStyle.Sizes.fontPixelSize
-            y: chartView.plotArea.y + EaStyle.Sizes.fontPixelSize
-            width: childrenRect.width
-            height: childrenRect.height
-
-            color: EaStyle.Colors.mainContentBackgroundHalfTransparent
-            border.color: EaStyle.Colors.chartGridLine
+Gui.SldChart {
+    id: sldChart
 
-            Column {
-                leftPadding: EaStyle.Sizes.fontPixelSize
-                rightPadding: EaStyle.Sizes.fontPixelSize
-                topPadding: EaStyle.Sizes.fontPixelSize * 0.5
-                bottomPadding: EaStyle.Sizes.fontPixelSize * 0.5
+    showLegend: Globals.Variables.showLegendOnSamplePage
+    reverseZAxis: Globals.Variables.reverseSldZAxis
 
-                Repeater {
-                    model: container.modelCount
-                    EaElements.Label {
-                        text: '━  SLD ' + Globals.BackendWrapper.sampleModels[index].label
-                        color: Globals.BackendWrapper.sampleModels[index].color
-                    }
-                }
-            }
-        }
-
-        EaElements.ToolTip {
-            id: dataToolTip
-
-            arrowLength: 0
-            textFormat: Text.RichText
-        }
-
-        // Zoom rectangle
-        Rectangle {
-            id: recZoom
-
-            property int xScaleZoom: 0
-            property int yScaleZoom: 0
-
-            visible: false
-            transform: Scale {
-                origin.x: 0
-                origin.y: 0
-                xScale: recZoom.xScaleZoom
-                yScale: recZoom.yScaleZoom
-            }
-            border.color: EaStyle.Colors.appBorder
-            border.width: 1
-            opacity: 0.9
-            color: "transparent"
-
-            Rectangle {
-                anchors.fill: parent
-                opacity: 0.5
-                color: recZoom.border.color
-            }
-        }
-
-        // Zoom with left mouse button
-        MouseArea {
-            id: zoomMouseArea
-
-            enabled: chartView.allowZoom
-            anchors.fill: chartView
-            acceptedButtons: Qt.LeftButton
-            onPressed: {
-                recZoom.x = mouseX
-                recZoom.y = mouseY
-                recZoom.visible = true
-            }
-            onMouseXChanged: {
-                if (mouseX > recZoom.x) {
-                    recZoom.xScaleZoom = 1
-                    recZoom.width = Math.min(mouseX, chartView.width) - recZoom.x
-                } else {
-                    recZoom.xScaleZoom = -1
-                    recZoom.width = recZoom.x - Math.max(mouseX, 0)
-                }
-            }
-            onMouseYChanged: {
-                if (mouseY > recZoom.y) {
-                    recZoom.yScaleZoom = 1
-                    recZoom.height = Math.min(mouseY, chartView.height) - recZoom.y
-                } else {
-                    recZoom.yScaleZoom = -1
-                    recZoom.height = recZoom.y - Math.max(mouseY, 0)
-                }
-            }
-            onReleased: {
-                const x = Math.min(recZoom.x, mouseX) - chartView.anchors.leftMargin
-                const y = Math.min(recZoom.y, mouseY) - chartView.anchors.topMargin
-                const width = recZoom.width
-                const height = recZoom.height
-                chartView.zoomIn(Qt.rect(x, y, width, height))
-                recZoom.visible = false
-            }
-        }
-
-        // Pan with left mouse button
-        MouseArea {
-            property real pressedX
-            property real pressedY
-            property int threshold: 1
-
-            enabled: !zoomMouseArea.enabled
-            anchors.fill: chartView
-            acceptedButtons: Qt.LeftButton
-            onPressed: {
-                pressedX = mouseX
-                pressedY = mouseY
-            }
-            onMouseXChanged: Qt.callLater(update)
-            onMouseYChanged: Qt.callLater(update)
-
-            function update() {
-                const dx = mouseX - pressedX
-                const dy = mouseY - pressedY
-                pressedX = mouseX
-                pressedY = mouseY
-
-                if (dx > threshold)
-                    chartView.scrollLeft(dx)
-                else if (dx < -threshold)
-                    chartView.scrollRight(-dx)
-                if (dy > threshold)
-                    chartView.scrollUp(dy)
-                else if (dy < -threshold)
-                    chartView.scrollDown(-dy)
-            }
-        }
-
-        // Reset axes with right mouse button
-        MouseArea {
-            anchors.fill: chartView
-            acceptedButtons: Qt.RightButton
-            onClicked: chartView.resetAxes()
-        }
-
-        Component.onCompleted: {
-            Globals.References.pages.sample.mainContent.sldView = chartView
-        }
-    }
-
-    // Create series dynamically when model count changes
-    onModelCountChanged: {
-        Qt.callLater(recreateAllSeries)
-    }
-
-    // Refresh all chart series when data changes
-    Connections {
-        target: Globals.BackendWrapper
-        function onSamplePageDataChanged() {
-            refreshAllCharts()
-        }
-    }
+    onShowLegendChanged: Globals.Variables.showLegendOnSamplePage = showLegend
 
     Component.onCompleted: {
-        Qt.callLater(recreateAllSeries)
-    }
-
-    function recreateAllSeries() {
-        // Remove old series
-        for (let i = 0; i < sldSeries.length; i++) {
-            if (sldSeries[i]) {
-                chartView.removeSeries(sldSeries[i])
-            }
-        }
-        sldSeries = []
-
-        // Create new series for each model
-        const models = Globals.BackendWrapper.sampleModels
-        for (let k = 0; k < models.length; k++) {
-            const line = chartView.createSeries(ChartView.SeriesTypeLine, models[k].label, axisX, axisY)
-            line.color = models[k].color
-            line.width = 2
-            line.useOpenGL = EaGlobals.Vars.useOpenGL
-            // Connect hovered signal for tooltip
-            line.hovered.connect((point, state) => showMainTooltip(chartView, point, state))
-            sldSeries.push(line)
-        }
-
-        refreshAllCharts()
-    }
-
-    function refreshAllCharts() {
-        const models = Globals.BackendWrapper.sampleModels
-        for (let i = 0; i < sldSeries.length && i < models.length; i++) {
-            const series = sldSeries[i]
-            if (series) {
-                series.clear()
-                const points = Globals.BackendWrapper.plottingGetSldDataPointsForModel(i)
-                for (let p = 0; p < points.length; p++) {
-                    series.append(points[p].x, points[p].y)
-                }
-            }
-        }
-    }
-
-    // Logic
-    function showMainTooltip(chart, point, state) {
-        if (!chartView.allowHover) {
-            return
-        }
-        const pos = chart.mapToPosition(Qt.point(point.x, point.y))
-        dataToolTip.x = pos.x
-        dataToolTip.y = pos.y
-        dataToolTip.text = `<p align="left">x: ${point.x.toFixed(3)}<br\>y: ${point.y.toFixed(3)}</p>`
-        dataToolTip.parent = chart
-        dataToolTip.visible = state
+        Globals.References.pages.sample.mainContent.sldView = sldChart.chartView
     }
 }
 
diff --git a/EasyReflectometryApp/Gui/Pages/Sample/Sidebar/Advanced/Groups/PlotControl.qml b/EasyReflectometryApp/Gui/Pages/Sample/Sidebar/Advanced/Groups/PlotControl.qml
index f7d77177..b448193c 100644
--- a/EasyReflectometryApp/Gui/Pages/Sample/Sidebar/Advanced/Groups/PlotControl.qml
+++ b/EasyReflectometryApp/Gui/Pages/Sample/Sidebar/Advanced/Groups/PlotControl.qml
@@ -17,6 +17,16 @@ EaElements.GroupBox {
     Column {
         spacing: EaStyle.Sizes.fontPixelSize * 0.5
 
+        EaElements.CheckBox {
+            topPadding: 0
+            checked: Globals.BackendWrapper.plottingPlotRQ4
+            text: qsTr("Plot R(q)×q⁴")
+            ToolTip.text: qsTr("Checking this box will plot R(q) multiplied by q⁴")
+            onToggled: {
+                Globals.BackendWrapper.plottingTogglePlotRQ4()
+            }
+        }
+
         EaElements.CheckBox {
             topPadding: 0
             checked: Globals.Variables.reverseSldZAxis
diff --git a/EasyReflectometryApp/Gui/Pages/Sample/Sidebar/Basic/Groups/Assemblies/MultiLayer.qml b/EasyReflectometryApp/Gui/Pages/Sample/Sidebar/Basic/Groups/Assemblies/MultiLayer.qml
index 213ab528..8697204f 100644
--- a/EasyReflectometryApp/Gui/Pages/Sample/Sidebar/Basic/Groups/Assemblies/MultiLayer.qml
+++ b/EasyReflectometryApp/Gui/Pages/Sample/Sidebar/Basic/Groups/Assemblies/MultiLayer.qml
@@ -78,6 +78,7 @@ EaElements.GroupColumn {
                 horizontalAlignment: Text.AlignHCenter
                 enabled: Globals.BackendWrapper.sampleLayers[index].thickness_enabled === "True"
                 text: (isNaN(Globals.BackendWrapper.sampleLayers[index].thickness)) ? '--' : Number(Globals.BackendWrapper.sampleLayers[index].thickness).toFixed(2)
+                onActiveFocusChanged: if (activeFocus && Globals.BackendWrapper.sampleCurrentLayerIndex !== index) Globals.BackendWrapper.sampleSetCurrentLayerIndex(index)
                 onEditingFinished: Globals.BackendWrapper.sampleSetCurrentLayerThickness(text)
             }
 
@@ -85,6 +86,7 @@ EaElements.GroupColumn {
                 horizontalAlignment: Text.AlignHCenter
                 enabled: Globals.BackendWrapper.sampleLayers[index].roughness_enabled === "True"
                 text: (isNaN(Globals.BackendWrapper.sampleLayers[index].roughness)) ? '--' : Number(Globals.BackendWrapper.sampleLayers[index].roughness).toFixed(2)
+                onActiveFocusChanged: if (activeFocus && Globals.BackendWrapper.sampleCurrentLayerIndex !== index) Globals.BackendWrapper.sampleSetCurrentLayerIndex(index)
                 onEditingFinished: Globals.BackendWrapper.sampleSetCurrentLayerRoughness(text)
             }
 
diff --git a/EasyReflectometryApp/Gui/Pages/Sample/Sidebar/Basic/Groups/Assemblies/SurfactantLayer.qml b/EasyReflectometryApp/Gui/Pages/Sample/Sidebar/Basic/Groups/Assemblies/SurfactantLayer.qml
index dd33ea8d..231e02f1 100644
--- a/EasyReflectometryApp/Gui/Pages/Sample/Sidebar/Basic/Groups/Assemblies/SurfactantLayer.qml
+++ b/EasyReflectometryApp/Gui/Pages/Sample/Sidebar/Basic/Groups/Assemblies/SurfactantLayer.qml
@@ -60,6 +60,7 @@ EaElements.GroupColumn {
             EaComponents.TableViewTextInput {
                 horizontalAlignment: Text.AlignHCenter
                 text: Globals.BackendWrapper.sampleLayers[index].formula
+                onActiveFocusChanged: if (activeFocus && Globals.BackendWrapper.sampleCurrentLayerIndex !== index) Globals.BackendWrapper.sampleSetCurrentLayerIndex(index)
                 onEditingFinished: Globals.BackendWrapper.sampleSetCurrentLayerFormula(text)
             }
 
@@ -67,6 +68,7 @@ EaElements.GroupColumn {
                 horizontalAlignment: Text.AlignHCenter
                 enabled: Globals.BackendWrapper.sampleLayers[index].thickness_enabled === "True"
                 text: (isNaN(Globals.BackendWrapper.sampleLayers[index].thickness)) ? '--' : Number(Globals.BackendWrapper.sampleLayers[index].thickness).toFixed(2)
+                onActiveFocusChanged: if (activeFocus && Globals.BackendWrapper.sampleCurrentLayerIndex !== index) Globals.BackendWrapper.sampleSetCurrentLayerIndex(index)
                 onEditingFinished: Globals.BackendWrapper.sampleSetCurrentLayerThickness(text)
             }
 
@@ -74,12 +76,14 @@ EaElements.GroupColumn {
                 horizontalAlignment: Text.AlignHCenter
                 enabled: Globals.BackendWrapper.sampleLayers[index].roughness_enabled === "True"
                 text: (isNaN(Globals.BackendWrapper.sampleLayers[index].roughness)) ? '--' : Number(Globals.BackendWrapper.sampleLayers[index].roughness).toFixed(2)
+                onActiveFocusChanged: if (activeFocus && Globals.BackendWrapper.sampleCurrentLayerIndex !== index) Globals.BackendWrapper.sampleSetCurrentLayerIndex(index)
                 onEditingFinished: Globals.BackendWrapper.sampleSetCurrentLayerRoughness(text)
             }
 
             EaComponents.TableViewTextInput {
                 horizontalAlignment: Text.AlignHCenter
                 text: (isNaN(Globals.BackendWrapper.sampleLayers[index].solvation)) ? '--' : Number(Globals.BackendWrapper.sampleLayers[index].solvation).toFixed(2)
+                onActiveFocusChanged: if (activeFocus && Globals.BackendWrapper.sampleCurrentLayerIndex !== index) Globals.BackendWrapper.sampleSetCurrentLayerIndex(index)
                 onEditingFinished: Globals.BackendWrapper.sampleSetCurrentLayerSolvation(text)
             }
 
@@ -87,6 +91,7 @@ EaElements.GroupColumn {
                 horizontalAlignment: Text.AlignHCenter
                 enabled: Globals.BackendWrapper.sampleLayers[index].apm_enabled === "True"
                 text: (isNaN(Globals.BackendWrapper.sampleLayers[index].apm)) ? '--' : Number(Globals.BackendWrapper.sampleLayers[index].apm).toFixed(2)
+                onActiveFocusChanged: if (activeFocus && Globals.BackendWrapper.sampleCurrentLayerIndex !== index) Globals.BackendWrapper.sampleSetCurrentLayerIndex(index)
                 onEditingFinished: Globals.BackendWrapper.sampleSetCurrentLayerAPM(text)
             }
 
@@ -108,7 +113,7 @@ EaElements.GroupColumn {
                 }
             }
             mouseArea.onPressed: {
-                if (Globals.BackendWrapper.samplCurrentLayerIndex !== index) {
+                if (Globals.BackendWrapper.sampleCurrentLayerIndex !== index) {
                     Globals.BackendWrapper.sampleSetCurrentLayerIndex(index)
                 }
             }
diff --git a/EasyReflectometryApp/Gui/Pages/Sample/Sidebar/Basic/Groups/LoadSample.qml b/EasyReflectometryApp/Gui/Pages/Sample/Sidebar/Basic/Groups/LoadSample.qml
index 14973e97..04235b1f 100644
--- a/EasyReflectometryApp/Gui/Pages/Sample/Sidebar/Basic/Groups/LoadSample.qml
+++ b/EasyReflectometryApp/Gui/Pages/Sample/Sidebar/Basic/Groups/LoadSample.qml
@@ -1,5 +1,5 @@
-import QtQuick 2.14
-import QtQuick.Controls 2.14
+import QtQuick
+import QtQuick.Controls
 import QtQuick.Dialogs
 
 import EasyApp.Gui.Style as EaStyle
@@ -13,6 +13,13 @@ EaElements.GroupBox {
     collapsed: false
 
     EaElements.GroupColumn {
+        EaElements.CheckBox {
+            id: appendCheckBox
+            text: qsTr("Append to existing models")
+            checked: true
+            width: EaStyle.Sizes.sideBarContentWidth
+        }
+
         EaElements.SideBarButton {
             width: EaStyle.Sizes.sideBarContentWidth
             fontIcon: "folder-open"
@@ -24,7 +31,31 @@ EaElements.GroupBox {
             id: fileDialog
             title: qsTr("Select a sample file")
             nameFilters: [ "ORT files (*.ort)", "ORSO files (*.orso)", "All files (*.*)" ]
-            onAccepted: Globals.BackendWrapper.sampleFileLoad(selectedFiles[0])
+            onAccepted: Globals.BackendWrapper.sampleFileLoad(selectedFiles[0], appendCheckBox.checked)
+        }
+    }
+
+    // Warning dialog for sample load issues
+    EaElements.Dialog {
+        id: sampleLoadWarningDialog
+        title: qsTr("Sample Load Warning")
+        standardButtons: Dialog.Ok
+        closePolicy: Popup.CloseOnEscape | Popup.CloseOnPressOutside
+
+        property string warningMessage: ""
+
+        EaElements.Label {
+            text: sampleLoadWarningDialog.warningMessage
+            wrapMode: Text.WordWrap
+            width: Math.min(implicitWidth, EaStyle.Sizes.sideBarContentWidth * 1.5)
+        }
+    }
+
+    Connections {
+        target: Globals.BackendWrapper
+        function onSampleLoadWarning(message) {
+            sampleLoadWarningDialog.warningMessage = message
+            sampleLoadWarningDialog.open()
         }
     }
 }
\ No newline at end of file
diff --git a/EasyReflectometryApp/Gui/PlotControlRefLines.qml b/EasyReflectometryApp/Gui/PlotControlRefLines.qml
new file mode 100644
index 00000000..e1ee3eeb
--- /dev/null
+++ b/EasyReflectometryApp/Gui/PlotControlRefLines.qml
@@ -0,0 +1,55 @@
+// SPDX-FileCopyrightText: 2025 EasyReflectometry contributors <support@easyreflectometry.org>
+// SPDX-License-Identifier: BSD-3-Clause
+// © 2025 Contributors to the EasyReflectometry project <https://github.com/easyscience/EasyReflectometry>
+
+import QtQuick
+import QtQuick.Controls
+
+import EasyApp.Gui.Style as EaStyle
+import EasyApp.Gui.Elements as EaElements
+
+import Gui.Globals as Globals
+
+Column {
+    spacing: EaStyle.Sizes.fontPixelSize * 0.5
+
+    EaElements.CheckBox {
+        topPadding: 0
+        checked: Globals.BackendWrapper.plottingPlotRQ4
+        text: qsTr("Plot R(q)×q⁴")
+        ToolTip.text: qsTr("Checking this box will plot R(q) multiplied by q⁴")
+        onToggled: {
+            Globals.BackendWrapper.plottingTogglePlotRQ4()
+        }
+    }
+
+    EaElements.CheckBox {
+        topPadding: 0
+        checked: Globals.Variables.logarithmicQAxis
+        text: qsTr("Logarithmic q-axis")
+        ToolTip.text: qsTr("Checking this box will make the q-axis logarithmic")
+        onToggled: {
+            Globals.Variables.logarithmicQAxis = checked
+        }
+    }
+
+    EaElements.CheckBox {
+        topPadding: 0
+        checked: Globals.BackendWrapper.plottingScaleShown
+        text: qsTr("Show scale line")
+        ToolTip.text: qsTr("Checking this box will show the scale reference line on the plot")
+        onToggled: {
+            Globals.BackendWrapper.plottingFlipScaleShown()
+        }
+    }
+
+    EaElements.CheckBox {
+        topPadding: 0
+        checked: Globals.BackendWrapper.plottingBkgShown
+        text: qsTr("Show background line")
+        ToolTip.text: qsTr("Checking this box will show the background reference line on the plot")
+        onToggled: {
+            Globals.BackendWrapper.plottingFlipBkgShown()
+        }
+    }
+}
diff --git a/EasyReflectometryApp/Gui/SldChart.qml b/EasyReflectometryApp/Gui/SldChart.qml
new file mode 100644
index 00000000..908b28b3
--- /dev/null
+++ b/EasyReflectometryApp/Gui/SldChart.qml
@@ -0,0 +1,388 @@
+// SPDX-FileCopyrightText: 2025 EasyReflectometry contributors <support@easyreflectometry.org>
+// SPDX-License-Identifier: BSD-3-Clause
+// © 2025 Contributors to the EasyReflectometry project <https://github.com/easyscience/EasyReflectometry>
+
+import QtQuick
+import QtQuick.Controls
+import QtCharts
+
+import EasyApp.Gui.Style as EaStyle
+import EasyApp.Gui.Globals as EaGlobals
+import EasyApp.Gui.Elements as EaElements
+
+import Gui.Globals as Globals
+
+
+Rectangle {
+    id: root
+
+    color: EaStyle.Colors.chartBackground
+
+    // Whether to show the legend (caller binds to the right page variable)
+    property bool showLegend: false
+
+    // Whether to show the z-axis reversed
+    property bool reverseZAxis: false
+
+    // Expose the ChartView so callers can store a reference / call resetAxes
+    readonly property alias chartView: chartView
+
+    // Track model count changes to refresh charts
+    property int modelCount: Globals.BackendWrapper.sampleModels.length
+
+    // Store dynamically created series
+    property var sldSeries: []
+
+    ChartView {
+        id: chartView
+
+        anchors.fill: parent
+        anchors.topMargin: EaStyle.Sizes.toolButtonHeight - EaStyle.Sizes.fontPixelSize - 1
+        anchors.margins: -12
+
+        antialiasing: true
+        legend.visible: false
+        backgroundRoundness: 0
+        backgroundColor: EaStyle.Colors.chartBackground
+        plotAreaColor: EaStyle.Colors.chartPlotAreaBackground
+
+        property bool allowZoom: true
+        property bool allowHover: true
+
+        property double xRange: Globals.BackendWrapper.plottingSldMaxX - Globals.BackendWrapper.plottingSldMinX
+
+        ValueAxis {
+            id: axisX
+            titleText: "z (Å)"
+            property double minAfterReset: Globals.BackendWrapper.plottingSldMinX - chartView.xRange * 0.01
+            property double maxAfterReset: Globals.BackendWrapper.plottingSldMaxX + chartView.xRange * 0.01
+            reverse: root.reverseZAxis
+            color: EaStyle.Colors.chartAxis
+            gridLineColor: EaStyle.Colors.chartGridLine
+            minorGridLineColor: EaStyle.Colors.chartMinorGridLine
+            labelsColor: EaStyle.Colors.chartLabels
+            titleBrush: EaStyle.Colors.chartLabels
+            Component.onCompleted: {
+                min = minAfterReset
+                max = maxAfterReset
+            }
+        }
+
+        property double yRange: Globals.BackendWrapper.plottingSldMaxY - Globals.BackendWrapper.plottingSldMinY
+
+        ValueAxis {
+            id: axisY
+            titleText: "SLD (10⁻⁶Å⁻²)"
+            property double minAfterReset: Globals.BackendWrapper.plottingSldMinY - chartView.yRange * 0.01
+            property double maxAfterReset: Globals.BackendWrapper.plottingSldMaxY + chartView.yRange * 0.01
+            color: EaStyle.Colors.chartAxis
+            gridLineColor: EaStyle.Colors.chartGridLine
+            minorGridLineColor: EaStyle.Colors.chartMinorGridLine
+            labelsColor: EaStyle.Colors.chartLabels
+            titleBrush: EaStyle.Colors.chartLabels
+            Component.onCompleted: {
+                min = minAfterReset
+                max = maxAfterReset
+            }
+        }
+
+        function resetAxes() {
+            axisX.min = axisX.minAfterReset
+            axisX.max = axisX.maxAfterReset
+            axisY.min = axisY.minAfterReset
+            axisY.max = axisY.maxAfterReset
+        }
+
+        // Tool buttons
+        Row {
+            id: toolButtons
+            z: 1
+
+            x: chartView.plotArea.x + chartView.plotArea.width - width
+            y: chartView.plotArea.y - height - EaStyle.Sizes.fontPixelSize
+
+            spacing: 0.25 * EaStyle.Sizes.fontPixelSize
+
+            EaElements.TabButton {
+                checked: root.showLegend
+                autoExclusive: false
+                height: EaStyle.Sizes.toolButtonHeight
+                width: EaStyle.Sizes.toolButtonHeight
+                borderColor: EaStyle.Colors.chartAxis
+                fontIcon: "align-left"
+                ToolTip.text: root.showLegend ?
+                                  qsTr("Hide legend") :
+                                  qsTr("Show legend")
+                onClicked: root.showLegend = checked
+            }
+
+            EaElements.TabButton {
+                checked: chartView.allowHover
+                autoExclusive: false
+                height: EaStyle.Sizes.toolButtonHeight
+                width: EaStyle.Sizes.toolButtonHeight
+                borderColor: EaStyle.Colors.chartAxis
+                fontIcon: "comment-alt"
+                ToolTip.text: qsTr("Show coordinates tooltip on hover")
+                onClicked: chartView.allowHover = checked
+            }
+
+            Item { height: 1; width: 0.5 * EaStyle.Sizes.fontPixelSize }  // spacer
+
+            EaElements.TabButton {
+                checked: !chartView.allowZoom
+                autoExclusive: false
+                height: EaStyle.Sizes.toolButtonHeight
+                width: EaStyle.Sizes.toolButtonHeight
+                borderColor: EaStyle.Colors.chartAxis
+                fontIcon: "arrows-alt"
+                ToolTip.text: qsTr("Enable pan")
+                onClicked: chartView.allowZoom = !checked
+            }
+
+            EaElements.TabButton {
+                checked: chartView.allowZoom
+                autoExclusive: false
+                height: EaStyle.Sizes.toolButtonHeight
+                width: EaStyle.Sizes.toolButtonHeight
+                borderColor: EaStyle.Colors.chartAxis
+                fontIcon: "expand"
+                ToolTip.text: qsTr("Enable box zoom")
+                onClicked: chartView.allowZoom = checked
+            }
+
+            EaElements.TabButton {
+                checkable: false
+                height: EaStyle.Sizes.toolButtonHeight
+                width: EaStyle.Sizes.toolButtonHeight
+                borderColor: EaStyle.Colors.chartAxis
+                fontIcon: "backspace"
+                ToolTip.text: qsTr("Reset axes")
+                onClicked: chartView.resetAxes()
+            }
+        }
+
+        // Legend showing all models
+        Rectangle {
+            visible: root.showLegend
+
+            x: chartView.plotArea.x + chartView.plotArea.width - width - EaStyle.Sizes.fontPixelSize
+            y: chartView.plotArea.y + EaStyle.Sizes.fontPixelSize
+            width: childrenRect.width
+            height: childrenRect.height
+
+            color: EaStyle.Colors.mainContentBackgroundHalfTransparent
+            border.color: EaStyle.Colors.chartGridLine
+
+            Column {
+                leftPadding: EaStyle.Sizes.fontPixelSize
+                rightPadding: EaStyle.Sizes.fontPixelSize
+                topPadding: EaStyle.Sizes.fontPixelSize * 0.5
+                bottomPadding: EaStyle.Sizes.fontPixelSize * 0.5
+
+                Repeater {
+                    model: root.modelCount
+                    EaElements.Label {
+                        text: '━  SLD ' + Globals.BackendWrapper.sampleModels[index].label
+                        color: Globals.BackendWrapper.sampleModels[index].color
+                    }
+                }
+            }
+        }
+
+        EaElements.ToolTip {
+            id: dataToolTip
+            arrowLength: 0
+            textFormat: Text.RichText
+        }
+
+        // Zoom rectangle
+        Rectangle {
+            id: recZoom
+
+            property int xScaleZoom: 0
+            property int yScaleZoom: 0
+
+            visible: false
+            transform: Scale {
+                origin.x: 0
+                origin.y: 0
+                xScale: recZoom.xScaleZoom
+                yScale: recZoom.yScaleZoom
+            }
+            border.color: EaStyle.Colors.appBorder
+            border.width: 1
+            opacity: 0.9
+            color: "transparent"
+
+            Rectangle {
+                anchors.fill: parent
+                opacity: 0.5
+                color: recZoom.border.color
+            }
+        }
+
+        // Zoom with left mouse button
+        MouseArea {
+            id: zoomMouseArea
+
+            enabled: chartView.allowZoom
+            anchors.fill: chartView
+            acceptedButtons: Qt.LeftButton
+            onPressed: {
+                recZoom.x = mouseX
+                recZoom.y = mouseY
+                recZoom.visible = true
+            }
+            onMouseXChanged: {
+                if (mouseX > recZoom.x) {
+                    recZoom.xScaleZoom = 1
+                    recZoom.width = Math.min(mouseX, chartView.width) - recZoom.x
+                } else {
+                    recZoom.xScaleZoom = -1
+                    recZoom.width = recZoom.x - Math.max(mouseX, 0)
+                }
+            }
+            onMouseYChanged: {
+                if (mouseY > recZoom.y) {
+                    recZoom.yScaleZoom = 1
+                    recZoom.height = Math.min(mouseY, chartView.height) - recZoom.y
+                } else {
+                    recZoom.yScaleZoom = -1
+                    recZoom.height = recZoom.y - Math.max(mouseY, 0)
+                }
+            }
+            onReleased: {
+                const x = Math.min(recZoom.x, mouseX) - chartView.anchors.leftMargin
+                const y = Math.min(recZoom.y, mouseY) - chartView.anchors.topMargin
+                const width = recZoom.width
+                const height = recZoom.height
+                chartView.zoomIn(Qt.rect(x, y, width, height))
+                recZoom.visible = false
+            }
+        }
+
+        // Pan with left mouse button
+        MouseArea {
+            property real pressedX
+            property real pressedY
+            property int threshold: 1
+
+            enabled: !zoomMouseArea.enabled
+            anchors.fill: chartView
+            acceptedButtons: Qt.LeftButton
+            onPressed: {
+                pressedX = mouseX
+                pressedY = mouseY
+            }
+            onMouseXChanged: Qt.callLater(update)
+            onMouseYChanged: Qt.callLater(update)
+
+            function update() {
+                const dx = mouseX - pressedX
+                const dy = mouseY - pressedY
+                pressedX = mouseX
+                pressedY = mouseY
+
+                if (dx > threshold)
+                    chartView.scrollLeft(dx)
+                else if (dx < -threshold)
+                    chartView.scrollRight(-dx)
+                if (dy > threshold)
+                    chartView.scrollUp(dy)
+                else if (dy < -threshold)
+                    chartView.scrollDown(-dy)
+            }
+        }
+
+        // Reset axes with right mouse button
+        MouseArea {
+            anchors.fill: chartView
+            acceptedButtons: Qt.RightButton
+            onClicked: chartView.resetAxes()
+        }
+    }
+
+    // Create series dynamically when model count changes
+    onModelCountChanged: {
+        Qt.callLater(recreateAllSeries)
+    }
+
+    // Refresh all chart series when data changes
+    Connections {
+        target: Globals.BackendWrapper
+        function onSamplePageDataChanged() {
+            refreshAllCharts()
+        }
+        function onSamplePageResetAxes() {
+            resetAxesTimer.start()
+        }
+        function onPlotModeChanged() {
+            refreshAllCharts()
+            resetAxesTimer.start()
+        }
+        function onChartAxesResetRequested() {
+            resetAxesTimer.start()
+        }
+    }
+
+    Timer {
+        id: resetAxesTimer
+        interval: 75
+        repeat: false
+        onTriggered: chartView.resetAxes()
+    }
+
+    Component.onCompleted: {
+        Qt.callLater(recreateAllSeries)
+    }
+
+    function recreateAllSeries() {
+        // Remove old series
+        for (let i = 0; i < sldSeries.length; i++) {
+            if (sldSeries[i]) {
+                chartView.removeSeries(sldSeries[i])
+            }
+        }
+        sldSeries = []
+
+        // Create new series for each model
+        const models = Globals.BackendWrapper.sampleModels
+        for (let k = 0; k < models.length; k++) {
+            const line = chartView.createSeries(ChartView.SeriesTypeLine, models[k].label, axisX, axisY)
+            line.color = models[k].color
+            line.width = 2
+            line.useOpenGL = EaGlobals.Vars.useOpenGL
+            line.hovered.connect((point, state) => showMainTooltip(point, state))
+            sldSeries.push(line)
+        }
+
+        refreshAllCharts()
+    }
+
+    function refreshAllCharts() {
+        const models = Globals.BackendWrapper.sampleModels
+        for (let i = 0; i < sldSeries.length && i < models.length; i++) {
+            const series = sldSeries[i]
+            if (series) {
+                series.clear()
+                const points = Globals.BackendWrapper.plottingGetSldDataPointsForModel(i)
+                for (let p = 0; p < points.length; p++) {
+                    series.append(points[p].x, points[p].y)
+                }
+            }
+        }
+    }
+
+    function showMainTooltip(point, state) {
+        if (!chartView.allowHover) {
+            return
+        }
+        const pos = chartView.mapToPosition(Qt.point(point.x, point.y))
+        dataToolTip.x = pos.x
+        dataToolTip.y = pos.y
+        dataToolTip.text = `<p align="left">x: ${point.x.toFixed(3)}<br\>y: ${point.y.toFixed(3)}</p>`
+        dataToolTip.parent = chartView
+        dataToolTip.visible = state
+    }
+}
diff --git a/EasyReflectometryApp/Gui/StatusBar.qml b/EasyReflectometryApp/Gui/StatusBar.qml
index cf92b436..9afb2c96 100644
--- a/EasyReflectometryApp/Gui/StatusBar.qml
+++ b/EasyReflectometryApp/Gui/StatusBar.qml
@@ -53,4 +53,11 @@ EaElements.StatusBar {
         valueText: Globals.BackendWrapper.statusVariables ?? ''
         ToolTip.text: qsTr('Number of parameters: total, free and fixed')
     }
+    EaElements.StatusBarItem {
+        visible: Globals.BackendWrapper.analysisFitChi2 > 0
+        keyIcon: 'chart-line'
+        keyText: qsTr('Chi²')
+        valueText: Globals.BackendWrapper.analysisFitChi2.toFixed(2)
+        ToolTip.text: qsTr('Goodness of fit (chi-squared)')
+    }
 }
diff --git a/EasyReflectometryApp/Gui/qmldir b/EasyReflectometryApp/Gui/qmldir
index d3151d58..fe68abae 100644
--- a/EasyReflectometryApp/Gui/qmldir
+++ b/EasyReflectometryApp/Gui/qmldir
@@ -1,4 +1,6 @@
 module Gui
 
 ApplicationWindow ApplicationWindow.qml
+PlotControlRefLines PlotControlRefLines.qml
+SldChart SldChart.qml
 StatusBar StatusBar.qml
diff --git a/pyproject.toml b/pyproject.toml
index 58c688b2..22977614 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -32,7 +32,7 @@ classifiers = [
 requires-python = '>=3.11'
 dependencies = [
   'EasyApp @ git+https://github.com/EasyScience/EasyApp.git@develop',
-  'easyreflectometry @ git+https://github.com/EasyScience/EasyReflectometryLib.git@append_sample',
+  'easyreflectometry @ git+https://github.com/EasyScience/EasyReflectometryLib.git@develop',
   'asteval',
   'PySide6',
   'toml',