bug#12251: 24.2.50; crash in note_mouse_highlight

[martin rudalics <rudalics@gmx.at>]

Maybe we've been miscommunicating, so let me try to sort things out:
We're trying to detect the source of a bug in note_mouse_highlight.  A
possible reason for this is that Emacs does not check the validity of
windows rigidly enough.  I added some checks in revision 109644.  The
patch I sent you does some more of these checks.

As a result of the checks from revision 109644 two problems turned up:

(1) In `set-window-configuration' the auto-buffer-name stuff didn't work
any more causing potential crashes or infinite looping here.  Neither of
these seem to show up in your scenario but I removed the stuff anyway in
revision 109802.

(2) Revision 109789 introduced a bug which caused your scenario

Debugger entered--Lisp error: (error "#<window 3> is not a live window")
   signal(error ("#<window 3> is not a live window"))
   error("%s is not a live window" #<window 3>)
   window-normalize-window(#<window 3> t)
   record-window-buffer(#<window 3>)
   set-window-configuration(#<window-configuration>)

I removed that in revision 109795 and hopefully fixed that for good in
revision 109803.  So this bug will show up in revisions 109789...109794.
If it shows up after revision 109794, something weird happens as I
mentioned before and I will have to investigate it with your help.

So please make sure that you work with the latest bzr version regardless
of whether you applied the patch I sent you or not.

martin