> The problem maybe be fixed, I feel.
 >
 > Sorry, I don't know the confirming method.
 > But, I've never got the rendering issue since applying your patch.
 >
 > Is this fine?

Hopefully.  It doesn't break the behavior under xfce/xfwm4.  I yet have
to test with Gnome and Plasma.  Meanwhile please do the following:

Apply the attached patch which adds a few diagnostics.  Then evaluate

   (setq frame-size-history '(100))

switch to the other virtual desktop, switch back to the Emacs
desktop, evaluate

   (frame--size-history frame)
   (pop-to-buffer "*frame-size-history*")

and tell me what *frame-size-history* contains now.

Then please do the same with Emacs _not_ focused before switching to the
other desktop.

And please also try the following: With emacs -Q put into *scratch*
the lines

(setq frame (make-frame))
(frame-visible-p frame)
(make-frame-invisible frame)
(make-frame-visible frame)
(iconify-frame frame)

Now use C-x C-e after any of these forms to first make FRAME and, for
example, make FRAME invisible, then make it iconified, then make it
visible and so on.  After every step use the `frame-visible-p' form to
check what Emacs thinks FRAME is.  If you find a transition that you
think is not correct, please tell me.

Thanks again, martin