However, if I call foo from a keybinding
((modMask, xK_x), foo)
the spawned program will run but not mapped. This means that I can see
the console output in xmonad stdout/stderr but the window will not pop
up. I think this is because of the internal handling of keyevents in
It's because your function is doing stuff instead of listening for X events. If you want to go off and do something else, forkIO a thread for the something else. If your something else requires communication with X11, you'll need to think about rewriting around the event handler instead.
code I have written. It's some kind of of vi-mode behaviour for xmonad.
XMonad.Actions.Submap would be a good starting point for this. Not an ideal one, as it doesn't support timeouts or grabbing an entire submap.