Dual (virtual) screen support under Xephyr (or Xnest)?

Paulo Zanoni przanoni at gmail.com
Fri Nov 26 08:00:11 PST 2010

If you have two screens on display :1 and want to open a xterm on each of them:
DISPLAY=:1.0 xterm
DISPLAY=:1.1 xterm

If you want to be able to move the mouse between the screens, you can
try using Xorg on top of Xorg with the "nestedv" driver. It's still in
veeery early development stage, but it allows you to have 2 screens
and use something like 'Screen "screen1" RightOf "screen2" in

There's a multi-screen xorg.conf example on the README file. You can
also use Option "Origin" to set the X/Y coordinates where the screens
will be opened on the bottom-layer X. Notice that if you want input
devices you'll have to read them directly from /dev/input (you still
can't get the input events from the bottom-layer Xorg, but luckly
there is a group of people working to solve this issue).


On Wed, Nov 24, 2010 at 1:06 PM, m h <sesquile at gmail.com> wrote:
> Hey Folks-
> I'm trying to debug some multiscreen issues with a wm [0] I'm
> contributing to.  This wm is scriptable so it makes development pretty
> cool, you write a test and it runs the tests in Xephyr.
> There are some issues with dual monitor support which I'd like to get
> ironed out.  Sadly I can't get Xephyr, Xdmx or Xnest to work with dual
> (virtual) screens.  It be great to test under them rather than using
> my real desktop.
> Here's what I've tried:
> # old command
> Xephyr -br +extension RANDR +xinerama -mouse evdev -screen 500x600
> -screen 400x300+500+0  :1 -ac & (sleep 1; env DISPLAY=:1
> ~/work/pylibs/qtile/qtile -d -c /home/matt/.config/qtile/mattdev.py  &
> env DISPLAY=:1 xterm)
> Brings up 2 windows, but I can't use xrandr to place them next to each
> other.  In fact xrandr only sees (can connect to) one of the windows.
> Both windows seem to overlap.
> # Xdmx attempt
> Xephyr :3.0 -a -ac -br +extension RANDR +xinerama -screen 300×400 &
> Xephyr :4.0 -a -ac -br +extension RANDR +xinerama -screen 200×400 &
> (sleep 2; Xdmx :5 -display localhost:3 -display localhost:4 +xinerama) &
> (sleep 4; env DISPLAY=:5 ~/work/pylibs/qtile/qtile -d -c
> /home/matt/.config/qtile/mattdev.py  & env DISPLAY=:5 xterm)
> Seems to bring up 2 windows next to each other, but doesn't want to
> let the wm draw anything other than windows:
> (**) dmx: dmxErrorHandler: RenderBadPicture (invalid Picture parameter)
> (**) dmx:                  Major opcode: 143 (RENDER)
> (**) dmx:                  Minor opcode: 10 (RenderTrapezoids)
> (**) dmx:                  ResourceID:   0x2000ae
> (**) dmx:                  Failed serial number:  1195
> (**) dmx:                  Current serial number: 1196
> # xnest
> Xnest :1 -ac -br +xinerama -scrns 2 -geometry 1000x500 & (sleep 1; env
> DISPLAY=:1 ~/work/pylibs/qtile/qtile -d -c
> /home/matt/.config/qtile/mattdev.py  & env DISPLAY=:1 xterm)
> This segfaults.
> I'm running on an intel t61p thinkpad with gentoo.  xorg 1.7.7, intel
> drivers 2.13.
> Any hints or suggestions would be wonderful.  As a last resort I could
> develop under my real (non-nested) wm.....
> thanks much!
> -matt
> 0 - http://www.qtile.org/
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Paulo Zanoni

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