bug#8789: 23.3; debug backtrace buffer changes window on step-through

[martin rudalics]

> Before, the same frame (seemingly) existed throughout.  I could hit `d' any
> number of times, and everything was smooth.  I could expand the frame size or
> reposition it, and it stayed wherever I put it.
>
> Now, it appears that each time I hit `d' the frame is deleted and a new frame 
is
> created to replace it.  And it is always re-created with the same, default 
size
> and position (top left of screen).

Try customizing `debugger-bury-or-kill'.

martin