bug#40278: 27.0.90; Flickering in Windows 10

[Eli Zaretskii]

> From: Noam Postavsky <npostavs@gmail.com>
> Cc: 40278@debbugs.gnu.org,  nicolasbertolo@gmail.com
> Date: Mon, 30 Mar 2020 13:15:39 -0400
> 
> The "flicker" part is that it looks like the window turns momentarily
> completely blank before redrawing.

That could happen if there's nothing in common between the previous
and the new contents of the window.  Again, if redisplay cannot keep
up, this is entirely normal, and any flicker related to such situation
is something we cannot do anything about.

> > What do you mean by "beneath" in this context?
> 
> There's occasionally a rectangle which seems to repainted slower than
> its surroundings.  That rectangle is lower down (closer to my desk than
> the ceiling) on my monitor than the child frame.  Also, I guess the text
> it momentarily contains was previously behind the child frame in terms
> of z-order (although it's a bit hard to tell because the repainting is
> still too fast to really anything).

What are the dimensions of that rectangle?  Is its width identical to
that of the parent frame, or is it smaller?  If smaller, is the width
similar to that of the child frame or different?