The 1.1 milestone has plans for "mouse-moved" and "modifiers-changed" events that you can register for, which would let you create a feature very similar to this, where if you hold down option and move the mouse, it will move the window under the mouse with it. I'll file an issue to investigate if it's possible to register for "mouse-clicked" events and override them to be no-ops (so that you don't actually click into the window). That sounds like a fun feature :)