bug#25851: 25.2; GTK warning when starting Emacs when desktop file has more than one frame

[N. Jackson]

Hi Martin,

At 10:01 +0100 on Friday 2017-03-24, martin rudalics wrote:
>
> Meanwhile please try my patch.  If after a week or so you don't see any
> troubles I intend to make it the default.

Sorry for the delay. I haven't used master for a while and it doesn't
like my init file. I've been spending my time on troubleshooting
that. But now I have things mostly up and running.

1. I am currently running master from earlier today which includes
your patch from the 23rd (commit
fe3af8d4f2a4cd67958f76d1b708e8a78e68cd4f) which I assume is the
one you want me to test?

2. I have not applied your proposed definition of
`xg_set_geometry' from Message #122
(https://debbugs.gnu.org/cgi/bugreport.cgi?bug=25851#122). [But I
still have that in my 25.2 rc2 Emacs, which is currently my
everyday Emacs.]

3. I have put

  (setq x-gtk-use-window-move t)

in the working part of my init file [the rest of my init file --
about 10% of it -- is commented out right now].

4. In my desktop file I have three frames specified each with
a distinctive size and position.

The result is that:

- Frames are successfully restored to their former size and
position.

- No GTK warning messages are being emitted.

However:

- When I switch between frames using the window manager Alt-tab
window switching, there is a big flash almost every time when an
Emacs frame is displayed. I've never seen this problem before.
(Occasionally I've seen a single line of the display flicker while
scrolling, but I've never seen Emacs make the whole screen flash
like this before.)

[The flash is too fast to describe other than to say it is light
in colour and appears to be horizontal, almost as if there is a
white or grey highlight being applied randomly to about half the
lines in the frame and then turned off again.]

[This was after I'd maximized the three frames so that I could use
them, rather than when they were the smaller size at which they
were specified in the desktop file I tested with. I tried
restoring them down to their previous size and didn't see the
flash, then maximised them again and the flashing was back. I
suppose that the flashing might also be happening when they're
small but that my eye isn't fast enough to detect it; not sure.]

Of course this flashing might be unrelated, it might be due to a
change elsewhere in master.


The display antics at startup are slightly different but still
there. The sequence seems to be (with three frames in my desktop
file with distinctive sizes and positions):

a) A largish light-colour-scheme frame is displayed.

b) It shrinks but is still a light colour scheme. (Presumably my
default font is applied here.)

c) It changes to a dark colour scheme. (Presumably my colour
scheme is being applied here.)

d) It sits there for a bit with the various startup messages
appearing in the echo area.

e) It disappears and the three frames in my init file appear.
(Alternative explanation: It changes its size and position to that
of one of the frames in my init file, and the other two frames
from my init file are displayed.)

These antics are different from with Emacs 25 where I never see a
light-colour-scheme frame unless I start with `-Q'.

I hope this helps. Please let me know if you have further
questions for me.

N.