or
I set the parameters in order to have a black background color in the scrollbar, but when both the scrollbars are visible appears a white square (it appears whatever color the background is). How can I avoid or delete this kind of effect?

public TelerikTreeview(){ InitializeComponent(); RadDragAndDropManager.AddDropQueryHandler(m_cellTreeView, new EventHandler<DragDropQueryEventArgs>(OnDropQuery));}private void OnDropQuery(object sender, DragDropQueryEventArgs e){ System.Diagnostics.Debug.WriteLine(e.Options.Effects);}