Re: Emacs's set-frame-size can not work well with gnome-shell?

[Dmitry Gutov]

On 19.01.2020 11:52, martin rudalics wrote:
>  > Maybe. But it might also mean that it's possible to provide some hint
>  > to the window manager that resizing is indeed allowed.
>
> Maybe.  But how would we find out?

By asking Mutter developers, maybe. Or reading Mutter code. Sorry, I'm 
not really qualified to do either.

> Did others try your "fix" already?

I've posted the patch to posframe, let's see what others say. But I'm 
seeing a reliable improvement.

>  > Do you have a compositing window manager (on your GNU/Linux system)?
>
> Xfce comes with compositing capabilities but my graphic card might not
> comply.  Setting an 'alpha' parameter for a child frame effectively does
> not work (it seemed to work on my Windows machine but that is broken now
> so I can't check).

If sending you a newer graphics card would help the situation, I'm game. :-)

Linux graphics drivers situation has been rather poor historically, so 
I'm not sure which one to choose.

> Mostly I don't care because normal Emacs frames
> always flicker during resizing anyway.

Even when resizing doesn't actually change the size?

>  > It doesn't flicker always, but like 3 out of 4 times is does. And 
> running resize-test in a loop always shows 1-2 flickers, at least.
>
> So when you now resize a child frame by dragging its corners, it usually
> flickers.

I still can't resize it by dragging its corners. The "dragging" code 
doesn't know to make the frame invisible/visible, and I don't know where 
to change that.

> It does not flicker at all here.  Probably because its buffer
> is empty, possibly because certain compositing effects are ignored or
> not implemented.

The buffer contents are the same for me.

>  >> You could try to play around with 'x-wait-for-event-timeout'.
>  >
>  > You mean to bind it to a larger value around the body of resize-test?
>  >
>  > I tried 1, as well as 10. No change.
>
> A floating point value less than 0.1.  Non-floating point values stand
> for 0 ("no wait").  It stands for waiting that many seconds for a
> configure notify event that would confirm that your frame has really
> become visible or invisible.  So IIUC (Noam might correct me) you may
> have to wait twice that time with WMs that don't send such events.

This is the usage you meant, right?

(defun resize-test (frame height)
  (let ((x-wait-for-event-timeout 0.05))
    (make-frame-invisible frame)
    (set-frame-height frame height)
    (make-frame-visible frame)))

I tried different values: 0.05, 0.001, 0.2, 0.5. The upshot, in this 
round of testing, is that it always flickers at least once. It might 
only flicker the mode-line and the scrollbar. Or it might flicker to 
show the contents of the underlying window. But that seems to happen 
regardless of the value above.