[winswitch] How to use "randr" to resize the desktop?

Antoine Martin antoine at nagafix.co.uk
Sat Dec 27 18:21:37 GMT 2014

Please don't top post. Again.

On 28/12/14 01:09, Heng Zhou wrote:
> I'm sorry I'm getting more and more confused. To run RandR, i.e.,
> xrandr, I have to use xpra to hold the whole desktop
This sounds like you have it backwards, but whatever.
> (if xpra forwards only application, the xpra window can resize at the
> client side. Yes it can), but the http://xpra.org/trac/wiki/Usage
> webpage requires using Xnest as a nested X11 server. I did not run
> Xdummy or Xvfb.
Xnest (or Xephyr) runs nested inside another X11 server, which can
either be Xdummy or Xvfb.
> Actually I don't know how to run Xdummy -- there is a command "xvfb"
> in ubuntu, but there is no command of Xdummy or xdummy. So I don't
> understand your reply "Xdummy supports RandR, Xvfb does not, hence the
> error.". I only run Xnest.
No you don't. Xpra runs a display server (either Xdummy or Xvfb) and you
start Xnest in it.
See the wiki page on Xdummy.
> Do you mean  Xnest is equivalent to Xdummy or Xvfb?
> For the former, Xdummy doesn't work on ubuntu so RANDR doesn't work.
> For the latter, Xvfb does not support GLX so metacity and all other
> OpenGL applications do not work. Am I right? If I am, which one is
> Xnest equivalent to?
Xpra supports OpenGL with Xdummy only.
AFAIK, even with Xdummy, you will not be able to get OpenGL with Xnest
or Xephyr, which you need for running a full desktop.
> And as for Xdummy, does it run automatically after I run xpra, so it
> is expected  that a virtual frame buffer, or a virtual graphics card
> exists on display :100 after xpra start :100, so I can run glxgears on
> a remote Red Hat machine (on display :100), e.g., Amazon EC2 Red Hat
> instance, without any trouble like those I encountered on ubuntu,
> right? Hopefully my understanding is right.
Yes, xpra starts the virtual display server when you run "xpra start".
> Gnome Panel is the only desktop I can use on Amazon EC2 instance,
> which appears only under Xnest. If I run Xephyr, the xpra window is
> black. There are bugs anywhere in Linux world.
Xephyr works fine here.

> On Sat, Dec 27, 2014 at 12:35 PM, Antoine Martin
> <antoine at nagafix.co.uk <mailto:antoine at nagafix.co.uk>> wrote:
>     Please don't top post.
>     On 28/12/14 00:25, Heng Zhou wrote:
>>     Thanks for the reply. So RandR only works at the server side
>>     (because window manage runs at server side); resizing at client
>>     side does not work, right?
>     Sort of. RandR has nothing to do with the window manager.
>     You can't resize client-side because the xpra protocol does not
>     support it yet.
>>     But after I run the following commands at the server side:
>>     (1) xpra start :100
>>     (2) sudo DISPLAY=:100 Xnest +extension RANDR :200 -ac -geometry
>>     800x600+24 &
>>     (3) Use Xpra Launcher to connect to the server. A 800x600 Xpra
>>     window comes out.
>>     (4) sudo DISPLAY=:200 metacity &
>>     There is an error: "Xlib:  extension "RANDR" missing on display
>>     ":200"."
>>     (5) sudo DISPLAY=:200 gnome-settings-daemon &
>>     (6) sudo DISPLAY=:200 gnome-panel &
>>     The GNOME Panel desktop environment appears
>>     (7) sudo DISPLAY=:200 xrandr --size 1024x768
>     Xdummy supports RandR, Xvfb does not, hence the error.
>     And don't run everything root...
>>     , I received an error: "RandR extension missing" and the size of
>>     the Xpra window containing the whole desktop is unchanged.
>     Like the error says...
>>     I don't know what is the matter. I also tried "sudo DISPLAY=:100
>>     xrandr --size 1024x768" but nothing is changed. It seems that the
>>     RANDR extension is not enabled on display :200 (or :100? I don't
>>     know), but how should I enable it?
>     By using Xdummy instead of Xvfb.
>>     I have already include the +extension RANDR option in step (2).
>>     Should I install some other packages? The server is running
>>     ubuntu 14.04.
>     And here is your problem again.
>>     Looking forward to your further clarification.
>     Let's just make it crystal clear: Ubuntu is creating all these
>     problems, either move away from it or be prepared to solve those
>     problems on your own.
>     Cheers
>     Antoine
>>     On Sat, Dec 27, 2014 at 10:25 AM, Antoine Martin
>>     <antoine at nagafix.co.uk <mailto:antoine at nagafix.co.uk>> wrote:
>>         On 27/12/14 22:18, Heng Zhou wrote:
>>         > Hi,
>>         >
>>         > I can display a whole desktop using the instruction in
>>         > http://xpra.org/trac/wiki/Usage
>>         <https://urldefense.proofpoint.com/v2/url?u=http-3A__xpra.org_trac_wiki_Usage&d=AwMDaQ&c=TqceLeU8_c9CVUat-eLTFu19-lyGiWSvB_skZXlxt8Q&r=P1ABBvTuGPmJbUz5MdDh1bh-eAJtxjX6QuAJblLMVsI&m=1BG4F5DZ3vJ_ekEvx6ohg66_W_6vaZGYLu45aaV4Xhg&s=CRmtgmFewhBiPiCYnV5HnSDle3JhNjU5JfjiTc-s4EQ&e=>.
>>         Now I hope I can miximize the window
>>         > containing the desktop if I double click the title bar of
>>         the xpra window,
>>         > just like miximizing a normal window in Windows.
>>         "Double-click-to-maximize" is going to be desktop environment
>>         specific,
>>         often mapped as a shortcut for the maximize button.
>>         In this case, it is not possible because the window has a
>>         fixed size,
>>         and for that reason the maximize button should be disabled too.
>>         > The same webpage says that
>>         > "you can resize the desktop using the standard "randr"
>>         desktop tools (and
>>         > not by resizing the window at present)", so I think this is
>>         the approach to
>>         > accomplish what I want.
>>         randr is the X11 protocol, you may use any tool that uses it, ie:
>>         xrandr -s 1024x768
>>         "man xrandr" for details
>>         >  But after search the internet, I still have no idea
>>         > how to do it. Could you please give me a step by step
>>         configuration to
>>         > accomplish miximizing the window containing the whole
>>         desktop by double
>>         > click?
>>         It cannot be done at present because the window has a fixed size.
>>         There is a ticket for that:
>>         http://xpra.org/trac/ticket/530
>>         <https://urldefense.proofpoint.com/v2/url?u=http-3A__xpra.org_trac_ticket_530&d=AwMDaQ&c=TqceLeU8_c9CVUat-eLTFu19-lyGiWSvB_skZXlxt8Q&r=P1ABBvTuGPmJbUz5MdDh1bh-eAJtxjX6QuAJblLMVsI&m=1BG4F5DZ3vJ_ekEvx6ohg66_W_6vaZGYLu45aaV4Xhg&s=IJoQJL9km27EPxWH7M0euPBBCMIJHubITJeczUGllN8&e=>
>>         It doesn't look hard to implement, I just haven't had the time.
>>         >  Thank you very much!
>>         Cheers
>>         Antoine
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