bug#12648: 24.2.50; display-buffer switches to another frame

[martin rudalics <rudalics@gmx.at>]

 >> IIUC that's what Chong's `inhibit-switch-frame' alist entry is meant
 >> for.  I haven't tried it yet, though.
 >
 > Is that supposed to fix the source-in-other-frame case without harming
 > the source-in-other-window case (which works correctly with the
 > current code in gud.el)?  If so, then all we need is to change gud.el
 > to use that entry.  If some people want the current behavior with
 > 'visible, then so be it; I only want to fix GUD, where I don't believe
 > anyone would want it.

IIUC a user can either set

  `reusable-frames' -- Value specifies frame(s) to search for a
                       window that already displays the buffer.
                       See `display-buffer-reuse-window'.

to nil so the buffer will get displayed on the selected frame even if it
is displayed somewhere elese, or set

  `inhibit-switch-frame' -- A non-nil value prevents any other
                            frame from being raised or selected,
                            even if the window is displayed there.

to t.  The semantics of the latter is not very clear to me because with
most window managers Emacs cannot prevent a new frame from being raised
and selected (at least that's what I've been told repeatedly).

martin