void SelectedProperties_Loaded(object sender, RoutedEventArgs e)
 {
     _viewmodel = this.DataContext as SelectedPropertiesViewModel;
     CreateControls();
 }
 void SelectedProperties_DataContextChanged(object sender, DependencyPropertyChangedEventArgs e)
 {
     _viewmodel = this.DataContext as SelectedPropertiesViewModel;
     CreateControls();
 }