XTerm scrolling in xorg-server @1.20.4_0

[Ken Cunningham]

looks like the double buffering is not enabled or functioning and xterm is writing directly into the display buffer rather than into the back buffer and blitting it.

> On Apr 2, 2019, at 04:28, Michael Dickens <michaelld at macports.org> wrote:
> 
> This issue started with the prior "xorg-server-devel" bump a while back. I just moved to iTerm2 for the interim; -very- impressed with that terminal manager! I still need Xterm for some things though ... sigh ... - MLD
> 
> On Mon, Apr 1, 2019, at 11:37 PM, Ken Cunningham wrote:
>>> Has anybody else noticed that text scrolling in a xterm is now glacially
>>> slow since xorg-server was upgraded to @1.20.4_0 over the weekend?
>>> X11 is really painful to use now.
>> 
>> It certainly is. There is something wrong with the screen redrawing in 
>> xterm now, it seems.
>> 
>> Ken