We do have planned to provide this feature in near future.
Currently, we are investigating this functionality for possible issues and side effects. Unfortunately, I am unable to provide firm estimate for when it will be available for RadFileExplorer. You can follow the development of this feature in our PITS: Public URL
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