private void ChooseElement_Executed(object sender, ExecutedRoutedEventArgs e) { var attr = DmxTree.SelectedItem as AttributeView; var a2 = DmxTree.SelectedValue as AttributeView; var select = new Controls.SelectElement(); select.Owner = App.Current.MainWindow; select.SelectedElement = (Element)attr.Value; select.DataContext = DataContext; if (select.ShowDialog() == true) { attr.Value = select.SelectedElement; e.Handled = true; } }