Description of problem:
I can consistently crash gnome-shell by creating a single window in the primary workspace, opening the overlay and attempting to drag that window to the second workspace.

Version-Release number of selected component (if applicable):
gnome-shell-2.91.93-3.fc15.x86_64

How reproducible:
Every time

Steps to Reproduce:
1. Start up GNOME in the gnome-shell environment
2. Open exactly one window (I tested both Firefox and gnome-terminal)
3. Open the gnome-shell overlay
4. Drag the window created in step 2 to the empty second virtual desktop
  
Actual results:
Gnome-shell crashes and restarts on the first attempt.
On the second attempt within a session, gnome-shell reports a critical failure and forces you to log out.

Expected results:
The window should move, but the first workspace should disappear and the second workspace should be promoted to 'workspace 1'


Additional info: