BUGS
* collapsed clients outside stacked mode don't always uncollapse when they receive focus
* various qiv brokenness
* dosbox won't grab the mouse

4.0
* Opaque managed moves. I know I've argued against it, but it may be doable.
* Clicking layout boxes should do useful things.
* Collapse/uncollapse frames with the keyboard.
* Open modes (to replace colmodes).
* Resizable managed area. Maybe. Struts seem to do everything this might.
* New dmenu, with real cursor; snarfable.