Launch DOSBox on a system that has multiple monitors.
Move DOSBox from the main monitor to a secondary monitor
Set DOSBox to full screen mode
DOSBox will go full screen on the second monitor
DOSBox goes full screen on the original monitor, and when someone comes out of full screen mode the DOSBox window will be be moved back to the main monitor
This bug was found using DOSBox version 0.74 on a MacBook Pro running Mac OS X 10,6,8