RE: Bug report: Using Cygwin-Xfree through Remote Desktop Sharing (RDP)

[Jean-Claude Gervais <jc dot gervais at videotron dot ca>]

OK, this is weird:

	Running with the default drawing engine -

	If I start XWin locally (and then run fluxbox) in -nodecoration mode on the
Windows XP machine, whose screen resolution is 1024x768@32bpp and go to a
Windows 2000 machine whose screen resolution is 800x600@32bpp and run RDP
client to connect back to the XP box (RDP@MaxRes24bpp), I get the Cygwin
screen, but it looks really gross and pixilated... Also the extent of the X
screen seems to go beyond the RDP client's borders, and RDP does not permit
scrolling the remote desktop.... Strange...

	I can disconnect RDP, reconnect RDP, and things don't get better or any
worse...

2nd test.

	I start XWin (fullscreen) in query mode and connect it to a machine running
Redhat 7.3.

	If I go to the Windows 2000 machine and connect to XP, I get XWin's Redhat
view, but it looks psychedelic. If go back to the Windows XP box and take
back control, I cannot see XWin's output anymore. Instead of a big white
square, I get nothing at all, although from what I can tell, I am still in
control of the Redhat machine.

	If I close XWin, go back to the Windows 2000 machine, connect to XP with
RDP and start Xwin (query mode), then I get Redhat's login screen and
everything is beautiful. I can log in, close the RDP connection to XP,
reconnect to XP with RDP, and everything is still hunky-dory. If I go back
to the XP machine and retake control by its console, the XWin window is
minimized and if I restore it, it is transparent like the test before and
will not draw anything even if I am still remotely controlling the Redhat
computer. If I then go back to the windows 2000 machine and reconnect to XP
with RDP, everything is perfect. XWin draws the Redhat view perfectly.

	What seems to be the problem here is that the XP machine and the Windows
2000 machine are running at different geometries. XP is 1024x768 and Windows
2000 is running 800x600. It seems like XWin cannot deal with a dynamically
changing display size. This is probably a limitation in X, I would bet. So
as long as the console manipulating XWin has the same geometry as the one
that was in use when XWin was started, XWin is fine.

	Now to run the same test with XWin -engine 1

	If I start XWin locally (and then run fluxbox) in -nodecoration mode on the
Windows XP machine, whose screen resolution is 1024x768@32bpp and go to a
Windows 2000 machine whose screen resolution is 800x600@32bpp and run RDP
client to connect back to the XP box (RDP@MaxRes24bpp), I get the Cygwin
screen, and it looks perfect. The extent of the X screen still seems to go
beyond the RDP client's borders, and RDP still does not permit scrolling the
remote desktop.

	I can disconnect RDP, reconnect RDP, and Xwin is unaffected and still draws
perfectly.

2nd test.

	I start XWin (fullscreen) in query mode and connect it to a machine running
Redhat 7.3.

	If I go to the Windows 2000 machine and connect to XP, I get XWin's Redhat
view, there is a slight dithering effect apparent on the desktop wallpaper,
maybe due to the view being converted from 32bpp to 24bpp by RDP. Dithering
aside, visually, everything is fine, except for the fact that I cannot see
the whole XWin window. If go back to the Windows XP box and take back
control, I can still see XWin's output and control the Redhat machine.
XWin's colors are fine, but XWin's window has gone from being fullscreen to
being about 800x600 and the outer edges of the Redhat screen are now clipped
out and lost. Even if I use taskmanager to send a MAXIMIZE command to XWin,
there is no effect; I cannot recover the lost display area.

	If I close XWin, go back to the Windows 2000 machine, connect to XP with
RDP and start Xwin (query mode), then I get Redhat's login screen and
everything is beautiful. I can log in, close the RDP connection to XP,
reconnect to XP with RDP, and everything is still hunky-dory. If I go back
to the XP machine and retake control by its console, the XWin window is no
longer fullscreen but it is still displaying perfectly and I can still
remotely control the Redhat computer. If I then go back to the windows 2000
machine and reconnect to XP with RDP, everything is perfect. XWin is back to
being fullscreen (on the smaller 800x600 display) and still draws the Redhat
view perfectly. Oddly enough, there were NO dithering artifacts present
during this run...

	Also, I seemed to notice that sometimes, the RDP client seemed to think
that the XWin window was busy and would send back the BUSY cursor whenever
the mouse was over XWin, but I didn't make a strict analysis of it, and its
late.

If there are any permutations you'd like me to try, let me know.

Jean-Claude



-----Original Message-----
From: cygwin-xfree-owner@cygwin.com [mailto:cygwin-xfree-owner@cygwin.com]On
Behalf Of Harold L Hunt II
Sent: Monday, September 09, 2002 12:05 PM
To: cygwin-xfree@cygwin.com
Subject: Re: Bug report: Using Cygwin-Xfree through Remote Desktop Sharing
(RDP)

Jean-Claude,

Repeat the entire scenario you described, but start XWin with the
``-engine 1'' parameter, e.g.
XWin -engine 1

The default graphics engine on Windows 2000/XP will be DirectDraw 4.0;
DirectDraw will probably have a problem with RDP --- I am surprised that
it works at all.  The ``-engine 1'' parameter will tell XWin to use GDI
DIBs (Device Independent Bitamps) and regular GDI BLTs (Bit-Block
Transfers) as the graphics engine; GDI will be less prone to having a
problem with RDP.

If RDP works with the GDI engine then I know exactly what to fix; if
not, I will have to pump you for some more information.

Harold

Jean-Claude Gervais wrote:

>This is complicated, so I'll try to be clear.
>
>Let's say you have machine A, which is a Windows XP machine that has Cygwin
>and Cygwin-XFree installed on it.
>You use A to connect to B. B is a machine running Linux and X.
>Everything so far works.
>Then you use machine C (a machine running Windows 2000) to remote-control
>machine A with Windows XP Remote Desktop Client (RDP).
>Machine C can use machine A's Cygwin-XFree connection and view machine B.
No
>problem.
>However, when machine C breaks its connection to machine A, machine A's
>Cygwin-XFree will no longer display machine B. It will instead display a
>white screen in Cygwin-XFree.
>Although I am pretty sure that A is still connected and controlling B, it
>can no longer see B's display.
>It seems like Remote Desktop Client mucks-up Cygwin-XFree.
>
>I hope that that was clear enough.
>
>Thanks.
>
>
>
>