bug#48413: 28.0.50; emacs does not repaint the window after switching workspaces in Xmonad

[martin rudalics]

>> Can you please try the attached patch and tell me whether it improves or
>> breaks things.
>
> Yes, it fixes things - frame is repainted correctly now.
>
> My attempt was similar, but I included more code alongside SET_FRAME_VISIBLE 
(same as in Expose handler):
>
> +              block_input ();
> +             SET_FRAME_VISIBLE (f, 1);
> +             if (FRAME_X_DOUBLE_BUFFERED_P (f))
> +                font_drop_xrender_surfaces (f);
> +              f->output_data.x->has_been_visible = true;
> +              SET_FRAME_GARBAGED (f);
> +              unblock_input ();
>
> I'm not very familiar with Emacs frame internals - we don't need all these 
here?

If I only knew.  If you come up with a patch that works OK for you and
does not break the

(defvar frame (make-frame))
(make-frame-invisible frame)
(frame-visible-p frame)

scenario (where the latter returns 'icon) I want to fix here, I'll
happily install that.

>> Relying on these for setting visibility will fail for anyone who doesn't
>> send us an Expose event.
>
> I agree, feels a little fragile.

It apparently has not bitten us so far but the Xlib manual is not very
clear in this regard.

martin