> There is no way for language switcher to use only modifier keys. X protocol itself doesn't support it and workarounds are too complicated (like getting grab on all input and re-inserting messages back).
Just tried. I've set up xkb to switch layout using my Ctrl key. Looks working. I also configured xbindkeys to run some command when I press Shift. Looks working too. Both X11 protocol and Xorg itself allow you to use modifier keys to switch language, or write a custom switcher to do that.
> Duh. I think it's obvious that there should be a special protocol for resolution changing apps.
Ehm... Two protocols, one for games, changing resolution, and another for tools, changing resolution? And how are you going to stop games from using protocol for tools? Create another third protocol to authorize them? ;)
In Xorg there're much simpler solutions to that. I already told you about Ctrl+Alt+Plus/Minus and suggested you to bind `xrandr` call to some hotkey. Alternatively you can create a simple "restorer.sh" script: