X colormap problem when viewed via Microsoft Remote Desktop

Jon Turney jon.turney@dronecode.org.uk
Mon Jan 30 13:54:00 GMT 2017

On 29/01/2017 03:16, jeff_schenck@att.net wrote:
> After a fairly recent update of cygwin, I now find that all my X
> windows (xterm, emacs, etc.) have color and font problems.  Non-x
> terminal windows are fine.  Windows 7 is running as a VM on an esxi
> hypervisor, so I view it remotely with Microsoft Remote Desktop.  It
> worked well on a previous cygwin release, but I don't have the exact
> date when it changed.  Also, I don't think the problem is with MRD
> because I see it with VNC also.

Thanks for reporting this problem.

"color and font problems" is a bit vague.  Can you upload a screenshot 
somewhere which illustrates this?

This is unlikely to be a problem with actual X colourmaps unless you are 
using antique X clients which use 8 bit visuals.

However, RDP can step down the display colour depth, whereas the colour 
depth of an X server root window cannot change, which can cause 
dithering to occur.

Additionally, sometimes DirectDraw rendering to RDP doesn't seem to work 
properly, for unknown reasons. (This is discussed briefly in [1])

Since this has started 'recently', I guess it might be related to the 
'-compositewm' option being turned on by default [2].

So, you might try starting the X server with a limited colour depth 
(e.g. '-depth 16'), or try the '-engine 1' or '-nocompositewm' options [3].

[1] https://x.cygwin.com/docs/ug/using-terminal-server.html
[2] https://cygwin.com/ml/cygwin-announce/2016-06/msg00045.html
[3] https://x.cygwin.com/docs/faq/cygwin-x-faq.html#q-command-line-args

Jon Turney
Volunteer Cygwin/X X Server maintainer

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