Beginning of support for popupdropper. Uncomment line 743 to have it cycle on and off.

Problems:
1) Isn't actually transparent, can't figure out why yet.
2) Scroll bars on QGV turned off, but there are noticeable outlines of where they'd be.
3) Doesn't completely draw in the entire window, seems like there's a pixel-wide border that it doesn't cover.
4) Main window doesn't redraw right when the QGV is deleted, even though there's a repaint called.