private void WordUpVertreterHandlingControl_OnIsVisibleChanged(object sender, DependencyPropertyChangedEventArgs e)
            {
            if (WordUpVertreterHandlerModelInstance == null)
                WordUpVertreterHandlerModelInstance = new WordUpVertreterHandlerModel();
	        WordUpVertreterHandlerModelInstance.ActualizeKlassenAndOrganisationen();
			}
 private void WordUpVertreterHandlerModelInstanceChanged(WordUpVertreterHandlerModel OldValue,
     WordUpVertreterHandlerModel NewValue)
     {
     }