OSX: Get application windows + bounds

Is there a way to get the list of windows from another application and their bounds. E.g. using F-Script or obj-c or any other way (except AppleScript) to access the window contents of a开发者_C百科nother (any other) Cocoa-based application and possibly modify it?

I am talking about 1) accessing the data (as http://the.layersapp.com/ does) and 2) modifying it

...externally

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See these Stack Overflow questions: Getting the main window of other app, getting the unique ID of another app in OS X. Basically, the two APIs you can use is Accessibility and CGWindow.