RadEditor does not offer the requested feature out-of-the box. Could you please explain what do you want to implement and if possible send a screenshot of it?
Do you want to place the menu control over the RadEditor's toolbar and execute the editor's commands (Bold, Italic, Underline, etc) from the menu items?
By the way have you tried by any chance the RibbonBar toolbar mode
the Telerik team
If you want to get updates on new releases, tips and tricks and sneak peeks at our product labs directly from the developers working on the RadControls for ASP.NET AJAX, subscribe to their blog feed