A couple of options I have been wondering about.
1)
Is it possible to have an option that would enable running a program on the host on switching, IE when both CRTL keys are pressed. It would run on the host regardless if it was on the guest machine when the keys pressed.
An option like '>
Something like that. I have a small program that switches the monitor input via I2C direct (if interested:
http://pastebin.com/6Hd0pafF). The program would need to be modified a little bit to not use a variable input. but to somehow detect what it's currently at and then switch to the opposite -- shouldn't be too hard.
2)
This would be useful for number idea one.
Instead of both CTRL keys, could the hotkey be something like CTRL+SHIFT+ALT+1 for the host, and then each guest would set an option of 2 through 9. Since this is really only good for dedicated graphics cards, the most I've heard of is 7 in one machine and that was a crazy build. A normal person would have two cards, namely MS Windows Gaming Rig and GNU/Linux. However, some may want three, which is very doable on most systems. So, CTRL+SHIFT+ALT+2 or +3 to get to the other systems.
It can connect into point one, as the cheap and dirty monitor switcher code takes an input and my monitor has three inputs, so a person could write code to switch anything to anything. The option could have a variable string that when called by your Input patches, would replace the variable place holder with the machine being called, IE:
'execonswitch=/usr/bin/monitorswitch %COMPNUM'
Or something like that.
Hope you like the ideas.
Jon