PD: Toggling transparency doesn't reset colors

src/App/Property.cpp

@@ -247,10 +247,22 @@ void Property::destroy(Property* p)
     }
 }
 
+bool Property::enableNotify(bool on)
+{
+    bool isNotify = isNotifyEnabled();
+    on ? StatusBits.reset(DisableNotify) : StatusBits.set(DisableNotify);
+    return isNotify;
+}
+
+bool Property::isNotifyEnabled() const
+{
+    return !StatusBits.test(DisableNotify);
+}
+
 void Property::touch()
 {
     PropertyCleaner guard(this);
-    if (father) {
+    if (father && isNotifyEnabled()) {
         father->onEarlyChange(this);
         father->onChanged(this);
     }
@@ -266,7 +278,9 @@ void Property::hasSetValue()
 {
     PropertyCleaner guard(this);
     if (father) {
-        father->onChanged(this);
+        if (isNotifyEnabled()) {
+            father->onChanged(this);
+        }
         if (!testStatus(Busy)) {
             Base::BitsetLocker<decltype(StatusBits)> guard(StatusBits, Busy);
             signalChanged(*this);

src/App/Property.h

@@ -70,44 +70,27 @@ public:
      */
     enum Status
     {
-        /// Whether a property is touched.
-        Touched = 0,
-        /// Whether a property can be modified.
-        Immutable = 1,
-        /// Whether a property is read-only for the property editor.
-        ReadOnly = 2,
-        /// Whether the property is hidden in the property editor.
-        Hidden = 3,
-        /// Whether a property is saved in the document.
-        Transient = 4,
-        /// To turn ON PropertyMaterial edit.
-        MaterialEdit = 5,
-        /// To turn OFF PropertyMaterialList edit.
-        NoMaterialListEdit = 6,
-        /// Whether a property is an output property.
-        Output = 7,
-        /// Whether a dynamic property can be removed.
-        LockDynamic = 8,
-        /// Prevents causing `Gui::Document::setModified()`.
-        NoModify = 9,
-        /// Whether to allow change in a partial document.
-        PartialTrigger = 10,
-        /// Whether to prevent to touch the owner for a recompute on property change.
-        NoRecompute = 11,
-        /// Whether a floating point number should be saved as single precision.
-        Single = 12,
-        /// For PropertyLists, whether the order of the elements is
-        /// relevant for the container using it.
-        Ordered = 13,
-        /// In case of expression binding, whether the expression on
-        /// restore and touch the object on value change.
-        EvalOnRestore = 14,
-        /// For internal use to avoid recursive signaling.
-        Busy = 15,
-        /// Whether the linked object should be copied on change of the property.
-        CopyOnChange = 16,
-        /// Whether the property editor should create a button for user defined editing.
-        UserEdit = 17,
+        Touched = 0,             // touched property
+        Immutable = 1,           // can't modify property
+        ReadOnly = 2,            // for property editor
+        Hidden = 3,              // for property editor
+        Transient = 4,           // for property container save
+        MaterialEdit = 5,        // to turn ON PropertyMaterial edit
+        NoMaterialListEdit = 6,  // to turn OFF PropertyMaterialList edit
+        Output = 7,              // same effect as Prop_Output
+        LockDynamic = 8,         // prevent being removed from dynamic property
+        NoModify = 9,            // prevent causing Gui::Document::setModified()
+        PartialTrigger = 10,     // allow change in partial doc
+        NoRecompute = 11,        // don't touch owner for recompute on property change
+        Single = 12,             // for save/load of floating point numbers
+        Ordered = 13,            // for PropertyLists whether the order of the elements is
+                                 // relevant for the container using it
+        EvalOnRestore = 14,      // In case of expression binding, evaluate the
+                                 // expression on restore and touch the object on value change.
+        Busy = 15,               // internal use to avoid recursive signaling
+        CopyOnChange = 16,       // for Link to copy the linked object on change of the property with this flag
+        UserEdit = 17,           // cause property editor to create button for user defined editing
+        DisableNotify = 18,      // do not propagate changes of the property to its container
 
         // The following bits are corresponding to PropertyType set when the
         // property added. These types are meant to be static, and cannot be
@@ -116,31 +99,19 @@ public:
 
         /// Mark the beginning of enum PropertyType bits.
         PropStaticBegin = 21,
-        /// Whether the property is dynamically added.
-        PropDynamic = 21,
-        /// Corresponds to Prop_NoPersist.
-        PropNoPersist = 22,
-        /// Corresponds to Prop_NoRecompute.
-        PropNoRecompute = 23,
-        /// Corresponds to Prop_ReadOnly.
-        PropReadOnly = 24,
-        /// Corresponds to Prop_Transient.
-        PropTransient = 25,
-        /// Corresponds to Prop_Hidden.
-        PropHidden = 26,
-        /// Corresponds to Prop_Output.
-        PropOutput = 27,
-        /// Mark the end of enum PropertyType bits.
+        PropDynamic = 21,        // indicating the property is dynamically added
+        PropNoPersist = 22,      // corresponding to Prop_NoPersist
+        PropNoRecompute = 23,    // corresponding to Prop_NoRecompute
+        PropReadOnly = 24,       // corresponding to Prop_ReadOnly
+        PropTransient = 25,      // corresponding to Prop_Transient
+        PropHidden = 26,         // corresponding to Prop_Hidden
+        PropOutput = 27,         // corresponding to Prop_Output
         PropStaticEnd = 28,
 
-        /// User defined status bit.
-        User1 = 28,
-        /// User defined status bit.
-        User2 = 29,
-        /// User defined status bit.
-        User3 = 30,
-        /// User defined status bit.
-        User4 = 31
+        User1 = 28,              // user-defined status
+        User2 = 29,              // user-defined status
+        User3 = 30,              // user-defined status
+        User4 = 31               // user-defined status
     };
 
     /// Construct a property.
@@ -354,11 +325,16 @@ public:
      */
     virtual void onContainerRestored() {}
 
-    /** @name Property status handling
-     * @{
+    /** Property status handling
      */
-
-    /// Set the property touched.
+    //@{
+    /// This method sets whether notification will be propagated on changing
+    /// the value of the property. The old value of the setting is returned.
+    bool enableNotify(bool on);
+    /// This method returns whether notification of changes to the property value
+    /// are propagated to the container.
+    bool isNotifyEnabled() const;
+    /// Set the property touched
     void touch();
 
     /**

src/Mod/PartDesign/Gui/ViewProviderBody.cpp

@@ -263,10 +263,23 @@ void ViewProviderBody::onChanged(const App::Property* prop) {
         // #0002559: Body becomes visible upon changing DisplayModeBody
         Visibility.touch();
     }
-    else
+    else {
         unifyVisualProperty(prop);
+    }
+
+    // When changing transparency then adjust the ShapeAppearance inside onChanged()
+    // of the base class but don't notify its container again. This breaks the chain of
+    // notification and avoids the call of onChanged() with the ShapeAppearance as argument
+    // This fixes issue https://github.com/FreeCAD/FreeCAD/issues/18075
+    if (prop == &Transparency) {
+        ShapeAppearance.enableNotify(false);
+    }
 
     PartGui::ViewProviderPartExt::onChanged(prop);
+
+    if (prop == &Transparency) {
+        ShapeAppearance.enableNotify(true);
+    }
 }