Using evolution with an Exchange mailbox illustrates this well, because it's a
I move 1 message from an Exchange mailbox to a local mailbox, then start moving
a second message from an Exchange mailbox to a local mailbox. I do this by
dragging and dropping.
If the first move completes before I have released the left mouse button for the
second move, the cursor stays as the "Move" cursor, permanently. I can't use my
mouse for anything else any more - for anything - clicking no longer works.
The workaround is to Ctrl+Alt+F1, then login, then kill evolution, and Ctrl+Alt+F7.
Thanks for the bug report. I'm going to move this to the upstream bug tracker
where I'll continue to track the problem. Please see  for further updates.