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

Heng Zhou hzhou1 at cs.uml.edu
Sat Dec 27 18:09:58 GMT 2014

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 (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. 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. 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?

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.

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.

On Sat, Dec 27, 2014 at 12:35 PM, Antoine Martin <antoine at nagafix.co.uk>

>  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>
> 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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