Subject: Re: bug#38497: 27.0.50; Frame is not rendered when frame-resize-pixelwise it 't

From: Eli Zaretskii <[email-masked]>
Date: Sun, 15 Dec 2019 17:21:41 +0200

> From: Ihor Radchenko <[email-masked]>
> Cc: [email-masked], [email-masked]
> Date: Sun, 15 Dec 2019 21:43:34 +0800
> 
> > That's unheard of.  Does redraw-display at least blank the entire
> > frame?
> 
> Nope. I don't see anything changing. 

That's impossible.  When you invoke redraw-display, Emacs on X calls
the function x_clear_frame, which calls x_clear_window, which calls
XClearWindow.  Do you see this sequence of calls if you step through
the code with a derbugger?

One possible reason for not clearing the frame is that you have
double-buffering enabled.  Can you disable it and try again?  (If you
don't know how, search for "double buffering" in etc/NEWS.26.)

Failing that, the only way I can explain this is that you have some
"optimization" feature in your video hardware and/or driver, and that
is the cause of all the problems you report in this thread.  Please
review the settings of your video driver software, and turn off any
"optimization" or "advanced" feature you find there.  If that doesn't
help, maybe upgrading to a newer version of the video driver will
help.