In OSX, how do I determine the position of windows, and which window is active?

I'm working on an idea for a type of window manager for OSX, similar to Cinch or SizeUp. In order to do this I need to be able to determine the positions of various windows, and which window is active. Some kind of callback when the active window changes would also be useful, as would how to handle multiple screens and multiple spaces.

I'm resigned to the fact that I'll开发者_如何学运维 probably need to learn Objective C for this, but if there is a way to do this type of thing from Java, that would be particularly awesome.

Can anyone point me to the appropriate place in the OSX API for these things?

You'll want to take a look at the Accessibility API, as discussed here.