Ref T225, force stylesheet in CForm base class and used by all forms

* Allows to use stylesheet attributes like [readonly]
* changing to "readonly" applies correct stylesheet

src/blackgui/editors/modelmappingmodifyform.cpp

@@ -88,6 +88,7 @@ namespace BlackGui
         {
             // void
             Q_UNUSED(readOnly);
+            // this->forceStyleSheetUpdate();
         }
 
         void CModelMappingModifyForm::userChanged()