private void UserControl_IsVisibleChanged(object sender, DependencyPropertyChangedEventArgs e)
{
if (!bindingInitialized && this.IsVisible)
{
Binding binding = new Binding("AvailableEditors");
binding.RelativeSource = new RelativeSource(RelativeSourceMode.FindAncestor, typeof(MainWindow), 1);
binding.NotifyOnTargetUpdated = true;
EditorSelection.SetBinding(ItemsControl.ItemsSourceProperty, binding);
bindingInitialized = true;
}
}