Comment #6 on issue 515 by allber...@gmail.com: XMonad freezes occasionally when using Gridselect (XMonadContrib) http://code.google.com/p/xmonad/issues/detail?id=515 You won't see it 100% consistently; even the infamous putSelect wasn't 100% consistent. I just went through the GridSelect code. There is no full server grab; the keyboard and one mouse button are grabbed, though. Beyond this, the issue is that xmonad is not processing events in its main loop, and this means (a) it cannot do things like switching workspaces; (b) events that GridSelect does not expect are simply dropped, meaning: (c) new windows will completely fail to do the window management process; (d) other potentially important X11 events and negotiations are dropped on the floor. Which means that there are a number of ways that GridSelect can lead to gridlock with either clients or the X11 server. If you pick your selection quickly, you likely won't notice; the longer GridSelect stays up, and the more things that happen while it's up, the more likely that xmonad will drop/ignore something critical.