#243 key-up event lost when using command-control-arrow

[Chris Petersen]

When switching to another Space from CotVNC, if I switch back, there is a command/control keydown event stuck in the vnc console (linux in my case), which causes confusion if you start typing letters. I believe this gets mapped to the "windows" key in my linux console (judging by the behavior). It would be nice if CotVNC would not allow itself to lose focus without sending keyup events for any current keydowns.

Current workaround is to just press command or control whenever CotVNC gains focus, just in case there are stuck events (sending one seems to clear out the rest).