I kinda hate to ask something "borrowed" from another program, but if you have ever played a GameMaker game, you'll know what I mean.
When you set the game to run in fullscreen, the window enlarges to match your desktop resolution, covering the entire screen, and also stretching the image without losing it's aspect ratio.
I thinks that is a great way, at least as an option, to do fullscreen.
I don't know if it'd be possible, but maybe what we need is an option the set the resolution for the visible part of the layouts and another screen resolution, that way we could change the second one, while the first stretches to match it.
I'm sorry if this sounds weird when you read it, my english writing skills obviously are from a non-native speaker