Previously, when an expose event was recieved, the backend would
call Window.paste, converting RGBA image data to BGRA image data.
Now we only call Window.pushRegion with the bounds given to us by
the expose event(s). This speeds up window resizing significantly.
The repeated bool was removed and instead key release events are
*only* sent when the key is actually let go. If an element wants to
listen to repeat presses, it can just listen to press events.
