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/fsdsetupform.cpp

@@ -88,6 +88,7 @@ namespace BlackGui
             CGuiUtility::checkBoxReadOnly(ui->cb_AircraftPartsSend, readonly);
             CGuiUtility::checkBoxReadOnly(ui->cb_FastPositionReceive, readonly);
             CGuiUtility::checkBoxReadOnly(ui->cb_FastPositionSend, readonly);
+            this->forceStyleSheetUpdate();
         }
 
         CStatusMessageList CFsdSetupForm::validate(bool nested) const