- installed an eventFilter for the Sliders in the Preferences tab such that only if a slider has focus the mouse wheel will change its value

- in Preferences made sure that the changes of the scrollbar no longer interfere with signalling changes

appGUI/GUIElements.py

@@ -1075,6 +1075,7 @@ class FCSliderWithSpinner(QtWidgets.QFrame):
         self.spinner.valueChanged.connect(self._on_spinner)
 
         self.valueChanged = self.spinner.valueChanged
+        self.slider.installEventFilter(self)
 
     def get_value(self) -> int:
         return self.spinner.get_value()
@@ -1090,6 +1091,12 @@ class FCSliderWithSpinner(QtWidgets.QFrame):
         slider_value = self.slider.value()
         self.spinner.set_value(slider_value)
 
+    def eventFilter(self, object, event):
+        if event.type() == QtCore.QEvent.Type.Wheel:
+            if not self.slider.hasFocus():
+                return True
+        return False
+
 
 class FCSpinner(QtWidgets.QSpinBox):
     returnPressed = QtCore.pyqtSignal()

appGUI/preferences/PreferencesUIManager.py

@@ -14,7 +14,7 @@ if '_' not in builtins.__dict__:
     _ = gettext.gettext
 
 
-class PreferencesUIManager:
+class PreferencesUIManager(QtCore.QObject):
 
     def __init__(self, defaults: AppDefaults, data_path: str, ui, inform, options):
         """
@@ -26,6 +26,7 @@ class PreferencesUIManager:
         :param inform:      a pyqtSignal used to display information's in the StatusBar of the GUI
         :param options:     a dict holding the current defaults loaded in the application
         """
+        super(PreferencesUIManager, self).__init__()
 
         self.defaults = defaults
         self.data_path = data_path
@@ -1239,6 +1240,9 @@ class PreferencesUIManager:
         Will color the Preferences tab text to Red color.
         :return:
         """
+        if isinstance(self.sender(), QtWidgets.QScrollBar):
+            return
+
         if self.preferences_changed_flag is False:
             self.inform.emit('[WARNING_NOTCL] %s' % _("Preferences edited but not saved."))