Problems with display resize over RDP connections

Sun Jul 18 15:45:00 GMT 2010

On 29/04/2010 03:49, Raul Acevedo wrote:
> Didn't X figure out how to dynamically change its display resolution long
> time ago?  (I remember the "good old days" when this really was fixed on
> server start up, and the only way to change it was to restart X.)  Isn't
> there some way to tell the X server, even if it's via a command line
> utility, that the display has been reconfigured?  Modern Linux desktops
> certainly let me do this.

It's true that X can handle display resolution changes with the RANDR 
extension, but support needs to be present in the DDX layer as well, and 
currently the XWin DDX doesn't have this.

I've been working on some changes to add this support, which seem to work ok 
and could use some wider testing.

* Add RANDR extension support to XWin DDX.

* In multiwindow or rootless mode handle the WM_DISPLAYCHANGE message sent 
when monitor resolution or number changes. Use RANDR to update the X screen 
size to the virtual desktop size (if -multiplemonitors was used) or to the 
monitor size (if -screen @monitor was used)

* In rooted mode, a new option -resize is added to control resizing mode. 
When -resize=randr mode is selected, the native window containing the root 
window has a resizing frame and resizing the frame will use RANDR to change 
the size of the X screen.  Likewise, RANDR changes of X screen size will 
update the size of the native window containing the root window.

I've uploaded a build including these changes at [1].  Perhaps you could try 
it out and see if it works for you?

Patches are rather large so they can be found at [2]


> This is definitely over a secure link.  I'm not 100% sure what protocol is
> used; I go through a web portal interface, so it's not like I'm running a
> VNC/RDP client directly.
> Thanks, >
> Raul
> On Apr 28, 2010, at 7:16 PM, Jim Reisert AD1C wrote:
>> My understanding is that the X server inherits the properties of the screen it's started on.  For example, if you normally have 2 monitors, and for some reason only 1 monitor is active, and you start Xwin there, if you then active the 2nd monitor, you can't move your Xterm window over there (or you can, but you can't do anything with it).
>> What is RDP?  I like LogMeIn for this sort of thing, as long as you're not on a secure (ie. VPN) connection.  I really HATE when you log into a remote system and it changes those screen properties. Then when you come into work, it's all messed up.
>> On 4/28/2010 12:38 PM, Raul Acevedo wrote:
>>> At work, my display is at 1280x1024.  When I RDP from home, I have a
>>> bigger screen so my work computer's desktop is resized to 1920x1200.  When
>>> this happens, X applications cannot display anything below 1024 pixels;
>>> below 1024 pixels nothing is displayed, and you can see the other
>>> application windows underneath the current X window below 1024 pixels.
>>> Is this a known issue?  It's a pain to restart X and my apps just to get
>>> X to properly adjust its display size.

This is mentioned in the XWin manpage as a bug.

Volunteer Cygwin/X X Server maintainer

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