Comment #9 on issue 317 by ale...@feldgendler.ru: Util.XSelection.putSelection repeatable hang http://code.google.com/p/xmonad/issues/detail?id=317 gdb shows that the process hangs in XNextEvent(), which probably means it's within the forked run of processEvent. "info threads" in gdb shows there's only one OS- level thread. Here is my version of what happened: forkIO doesn't have to create an actual thread, it can be a “lightweight” thread <http://hackage.haskell.org/packages/archive/ base/3.0.3.0/doc/html/GHC-Conc.html#v%3AforkIO>. So it works as though it were a real thread as long as you don't call into libraries. Because it's not a real thread, the other thread doesn't get a chance to run while XNextEvent() is hanging. Suggested solution: use forkOS instead of forkIO, as the documentation recommends for situations when threads make blocking library calls. -- You received this message because you are listed in the owner or CC fields of this issue, or because you starred this issue. You may adjust your issue notification preferences at: http://code.google.com/hosting/settings