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

Heng Zhou hzhou1 at cs.uml.edu
Tue Dec 30 02:56:55 GMT 2014

Sorry for the late reply. I was doing a research on X window server
architecture these days, but I still can not fully understand your reply. I
can not find any webpage in wikipedia titled "Xdummy". Btw, what do you
mean by "top post"? I don't understand this word. It seems like I am making
some mistake, but I don't mean to offend. It is often the case in forums, I
asked some technical questions in a polite way (at least as much as can),
but someone just becomes unhappy at my questions, downvoting my question,
or saying something I don't understand like "top post". Why someone
(everyone actually) is so hostile, so against me? What did I ever do to

On Sat, Dec 27, 2014 at 1:21 PM, Antoine Martin <antoine at nagafix.co.uk>

>  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
> <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=s4cE8D8ncT_oxTtJQTIOJ1am98qetHwGe47PDmhhM8M&s=oj6p_AsQVAOEfnMRHN7CZXDKajeIdJmwCrAmgd1-BOU&e=>
> 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?
> No.
>   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.
> Antoine
> On Sat, Dec 27, 2014 at 12:35 PM, Antoine Martin <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>
>> 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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>>> <https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.devloop.org.uk_mailman_listinfo_shifter-2Dusers&d=AwMDaQ&c=TqceLeU8_c9CVUat-eLTFu19-lyGiWSvB_skZXlxt8Q&r=P1ABBvTuGPmJbUz5MdDh1bh-eAJtxjX6QuAJblLMVsI&m=1BG4F5DZ3vJ_ekEvx6ohg66_W_6vaZGYLu45aaV4Xhg&s=fjfodKw_jha4_0QDvURC--gFJOJBI67BuMACVYe7-38&e=>

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