here is how i would do it.
window's events
onprojectilehit :-: self :-: playsound :-: glassbreak
[100]onprjectilehit :-: self :-: killbrick
onprojectilehit :-: self :-: setemitter :-: pongdelete
onrelay :-: setemitter :-: none
onprojectilehit :-: self :-: firerelayUP
put 1 brick on top of the window
Bricks Events
Onrelay :-: FireRelayDown
so basically, the window dies after 100 millesonds, and in that time the window emitts pongdelete emitter which is a few white squares that might make it looklike debris, and it fires relay up, and then the brick on top fires relay back down, which will stop the emitter.