Open Radar

 
Summary:
With a well-timed and well-placed cursor, you can can unearth a Quick Look panel that is useless, disruptive and not immediately obvious how to dismiss.

Steps to Reproduce:
1. Open something in Quick Look in the finder.
2. Close the Quick Look panel. It may help to do this with shift+esc, so you have ample time to think about the next step, but it's perfectly possible without.
3. During the closing animation, click and hold somewhere on the screen that was occupied by the Quick Look panel but is no longer.
4. Still holding the mouse button, move the cursor.

Expected Results:
Nothing particularly special. Perhaps whatever would have happened had I clicked and dragged on whatever was under my cursor at the time.

Actual Results:
A bizarre shell of a quick look panel, square-edged, movable but not resizable (once you release the mouse button), devoid of any information and only dismissible by re-opening Quick Look.