There appear to be issues regarding keyboard navigation of the RadFileExplorer. These issues are evident in the demo provided on:
http://demos.telerik.com/aspnet-ajax/fileexplorer/examples/default/defaultcs.aspx
Specifically, the issues are:
1. In Firefox, keyboard navigation of the tree does not work. Keyboard navigation of the grid is fine.
2. In IE(7+), whilst keyboard navigation of both the tree and the grid seem to work okay, navigation from the grid back to the tree is awkward (I have actually been unable to do it, so may be impossible). Forward navigation appears to be acceptable.