low-level system events

[abegel@media.mit.edu]

How can I tell if my application has been sent to the background?
I'm doing some low-level assebly drawing stuff that I want to 
disable if my application is not in the foreground. Right now, I do it
when the window that I'm drawing in gets deactivated, but if I have
a screen saver, the window isn't deactivated and will keep drawing
over the screen saver!

Also, when you change color-depth using the Monitors control panel, 
does it send out any apple events or low-level events that I can see? I need
to change palettes for different color depths, and need to know when
it has changed.

I could check when lisp gets resumed (they would have had to run another
program to change the color depth, and lisp would have gone into the
background) but I don't know when this happens or when I can detect it, 
either.

Thanks.

Andrew Begel
MIT Media Lab
Epistemology and Learning