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

[martin rudalics]

Thanks for the forensics.  They clarify things with Bug#48268.

> Specifically the commenting of SET_FRAME_VISIBLE(f, 1) causes the problem (if 
I uncomment that line, buffer redisplay starts to work correctly).
>
> Trying the same with XFCE doesn't give the error. I compared the sequences of X events received 
under different WMs, here's the lists (without "other", "MotionNotify" and key 
events, for brevity):
>
> Xmonad:
> 1. When switching to different workspace:
>     - FocusOut x3
>     - UnmapNotify x1
>     - LeaveNotify x2
>     - PropertyNotify x2
> 2. When switching back:
>     - MapNotify x1

Can you tell me why we do not SET_FRAME_VISIBLE when receiving the
MapNotify event here?  Probably because we are not yet visible - though
mapped but invisible is a queer state.

>     - VisibilityNotify x3

Maybe we should process VisibilityNotify events.

>     - Expose x4

Relying on these for setting visibility will fail for anyone who doesn't
send us an Expose event.

>     - EnterNotify x2
>     - FocusIn x2
>     - ClientMessage x1
>     - PropertyNotify x1
>     - FocusIn x1
>
> XFCE:
> 1. When switching to different workspace:
>     - FocusOut x2
>     - FocusIn x1
>     - FocusOut x2
>     - LeaveNotify x2
>     - UnmapNotify x1
>     - PropertyNotify x3
> 2. When switching back:
>     - VisibilityNotify x3
>     - Expose x4
>     - EnterNotify x2
>     - PropertyNotify x2
>     - FocusIn x2
>     - ClientMessage x1
>     - PropertyNotify x2
>     - FocusOut x2
>     - FocusIn x1
>     - FocusOut x2
>     - FocusIn x2

So here we don't get a MapNotify anyway when switching back and using
VisibilityNotify should be TRT.

martin