bug#7728: 24.0.50; GDB backtrace from abort

[martin rudalics]

> No, as Martin mentioned, save-window-excursion is the macro to use if
> you want to write code that breaks in "odd" cases (sidenote:
> one-buffer-per-frame is one of those "odd" cases that tend to trigger
> bugs in code using save-window-excursion, so you probably "often" suffer
> from those things, like me).

`save-window-excursion' is the macro never to use.  It should be used
exclusively for debugging and prototyping.  Application programmers who
prefer to work with multiple frames themselves should know best and
avoid `save-window-excursion' like the plague.  At least in "released"
code.  Anything else is masochism.

martin