On a Mac, check out Better Touch Tool. It can accept midi triggers as inputs and use them to trigger pre-programmed window sizes (as well as almost any OSX function and a million other things).On Windows, I believe AutoHotKey can resize windows, but I'm not sure how to trigger that from Isadora. Though since you're operating, it sounds like a pair of custom hotkeys (in and out of the scene) would do most of what you're hoping for.