Different issues with key grab.

This is a bug report to steer some attention to
the key grab code. There are a couple of issues:

- after tmpwm the grab is sometimes not there
  (I got newly reminded about that due to
   http://bugs.debian.org/711523, though I remember
   it being an old issue (luckily with proper WMs
   one can do newwm back and forth but that does
   not help users wanting to temporarily use something
   without much features like in that case).
- when using a program grabing the keyboard, too
  (like rdesktop) and then activating something else
  like xscreensaver results in ratpoison losing the grab.

        Bernhard R. Link