The 'Start' menu button in the task bar at the bottom of the screen (or normally at the bottom of the screen) seems to always remain in a pressed/depressed state once it's been pressed once. Although it's pressed in, it seems to remain working.
This appears to be a generic fvwm 2.2 bug; I've submitted bug report 509 to the FVWM bug tracking system at http://www.fvwm.org/ about it. It may already be fixed in the fvwm 2.3 branch, since there's an earlier bug report about the problem against one of the 2.1.* fvwm development series that's been closed as fixed.
*** This bug has been marked as a duplicate of 2686 ***