Disable functionality because it might accidently be invoked?

Shouldn't the requirement that the one being dragged be pre-selected
be requirement enough?  That way it won't happen through accidently
clicking it, because its already clicked.

Especially now that I can no longer refresh the file list by clicking
the _already selected_ folder, something taht got broken since 5.0...
 Now I have to click on a different folder, then back to the folder I
wanted to refresh...