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/modelmappingform.cpp

@@ -68,6 +68,7 @@ namespace BlackGui
             ui->le_Description->setReadOnly(readOnly);
             ui->le_ModelKey->setReadOnly(readOnly);
             ui->le_Name->setReadOnly(readOnly);
+            this->forceStyleSheetUpdate();
         }
 
         void CModelMappingForm::setSelectOnly()