I have seen you proposal for a signal-slot system and I have one remark to make: I'ld like to see the "event" that triggered the signal being given as parameter to the signal handler (slot) function. It allows one handler for all key up and down events on an object. (Do you want separate a-up, b-up, a-down, b-down functions?) --MathFox 13:33, 4 July 2009 (UTC)