bug#10805: 24.0.93; edebug-trace t may cause stuff being inserted into current buffer

[martin rudalics <rudalics@gmx.at>]

 > Maybe.  But please keep in mind that `edebug-trace-display' is about
 > _displaying_ a buffer.  We don't want the user to edit the trace buffer,
 > so calling `select-window' is in fact not necessary in this case.  The
 > former window is instantly re-selected by `edebug-trace-display'.

IIUC edebug conflates the concepts of displaying and popping to buffers.
Take `edebug-bounce-point':

   (save-excursion
     ;; If the buffer's currently displayed, avoid set-window-configuration.
     ---> Since `save-window-excursion' calls `set-window-configuration'
          we don't "avoid" anything here.
     (save-window-excursion
       (edebug-pop-to-buffer edebug-outside-buffer)
       ---> Here the `select-window' problem might strike as well.  But
            why should the window be selected?  To make `goto-char',
            `current-buffer' and `point' work?
       (goto-char edebug-outside-point)
       (message "Current buffer: %s Point: %s Mark: %s"
	       (current-buffer) (point)
	       (if (marker-buffer (edebug-mark-marker))
		   (marker-position (edebug-mark-marker)) "<not set>"))
       (edebug-sit-for arg)
       ---> Popping back to the original window as the _last_ action of
            a `save-window-excursion' doesn't make any sense.
       (edebug-pop-to-buffer edebug-buffer (car edebug-window-data)))))

This may select a window up to three times for the apparent single
purpose to display the context of a position in some buffer.

 > Please also note (another issue, but related) that if the trace buffer
 > is already visible in another (visible) frame, a new window pops up in
 > the current frame nevertheless, which is kind of annoying if source
 > files are spread over multiple frames.

Probably because `edebug-get-buffer-window' (aliased to
`get-buffer-window') is called with a nil ALL-FRAMES argument.  Try to
use another argument (you probably have to raise frames to make this
useful).

martin