A common issue with Telerik layouts is that a customized RadMenu can float above everything else on the page. When that happens, other controls on the page have a tendency to pop up behind the menu.
This article shows two ways to correct the z-order so the editor’s dialogs display properly. The first method lowers the menu’s z-index and is the cleaner, recommended fix. The second method raises the dialog window with client script and is useful when you need more targeted control.