bug#745: pop-to-buffer, frames, and input focus

[martin rudalics]

> Are you saying, that pop-to-buffer can't be used to select the window,
> the frame, and input focus at the same time?  If so, when should
> pop-to-buffer be used?  Aren't that unusual situations when
> pop-to-buffer should not also select the input focus?

With emacs -Q evaluating

(let ((pop-up-frames t)
      (buffer (get-buffer-create "foo")))
  (pop-to-buffer buffer))

here gets me a new frame on top of the previously selected one, the
window displaying buffer `foo' is the selected window, and when I now
start typing, characters get displayed in that window.  What did you
expect and what did you get?

> If you have any hints or guidelines how be a good buffer/window/frame
> citizen in different scenarios, that would be much appreciated.

I'm slightly confused because in your earlier scenario you bemoaned the
fact that the frame _was_ selected.  All I wanted to say that raising a
frame, giving it input focus, and _not_ selecting it might be difficult.

> I'm not using multiple frames myself, but I'm maintaining a package
> called SLIME[*] which is used by a number of people who use frames.  I'm
> not excited at all about rewriting a dozen or so uses of pop-to-buffer
> just to support multiple frames.  There are some variables like
> display-buffer-reuse-frames and special-display-buffer-names and I hoped
> that those variables were supposed to make it easy to support multiple
> frames without cluttering the source code.
>
> [*] http://www.common-lisp.net/project/slime/

I moved `pop-to-buffer' to window.el so you can easier try to play
around with it and propose a solution that fits your needs ;-)

> The docstring of display-buffer reads
> "Make buffer BUFFER-OR-NAME appear in some window but don't select it. ..."
> I think it be would less surprising if the input focus would not be switched
> to the new frame.

You have a point here but it's not up to me to decide that.

> If I do
>
>    emacs -Q -nw --eval '(save-window-excursion
>                           (let ((pop-up-frames t))
>                             (display-buffer (get-buffer-create "foo"))))'
>
> I end up in the "*scratch*" buffer not in "foo". It would be more
> consistent if the X11 version and the tty version would restore the
> input focus to the same frame.  The tty version is the behavior that I
> would expect.

When I do

(save-window-excursion
  (let ((pop-up-frames t))
    (display-buffer (get-buffer-create "foo"))))

in the *scratch* buffer I end up in `foo' - whether this is TRT I don't
know.  Doing a `save-window-excursion' on the command line is beyond my
comprehension.

martin