#2 Be selective about X events.

[Richard Rauch]

The code presently just turns on all X event types,
carte blanch---whether or not a given event is of
interest. All windows have ~all events turned on, all
of the time.

This makes it harder to debug, since you get spammed,
for example, by passive mouse motion, even if you don't
care where the mouse is.

Instead of turning on all events all of the time,
an event-set normalization routine could be called
everytime you set/unset callbacks. In callbacks.c,
this could be stuffed into the window-callback-setting
macro. That would take care of *most* of the cases;
I can only think of one other place, offhand, that
would need to set the event mask (when windows are
being destroyed, we clear the callbacks and should at
that point clear the mask, too).