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My new laptop has a big 16:9 screen, and I'm finding it hard to fully utilize it during the 95% of the time that I'm not watching HD movies on it.

I'd like to set it up as a kind of virtual dual screen by splitting the physical screen into two workspaces. I know I could arrange my windows manually, but I'd like to be able to maximize a window and have it only consume half the monitor, and have its pop up dialogs centered on its half-screen, that sort of thing.

Is there some kind of plug in available to do this?

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If you're using compiz you may find the grid plugin more straightforward, see my answer below. – kynan May 5 '12 at 13:03
up vote 15 down vote accepted

you can use 'fakexinerama' for achieving what you want:

 Fake Xinerama is a replacement libXinerama library that instead 
 of querying the XServer reads ~/.fakexinerama and provides fake 
 information about Xinerama screens based on this file. It can be 
 used to fake a Xinerama setup even on computers with just one monitor
 or to fake Xinerama setup other than one specified in the XServer 
 configuration (e.g. making one screen smaller when using two same 
 screens). It's probably only useful for developers.
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Thanks, this works perfectly, and better than I'd hoped actually. My docks, panel bars, and floating windows span the physical screen, but maximized and "full screen" apps (including my vmware guest instances) politely keep to their half of the screen. I'm pretty new to linux, so hacking at my display settings felt a bit risky, but there's not really much work involved. I'm documenting my exact steps for other linux amateurs (like myself) in an additional answer below. – David Mar 2 '10 at 9:30
Link is broken. Any idea where I could find this software? – Maxime Dec 19 '13 at 11:34

To expand on akira's tip above on using Lubos Lunak's "fake xinerama", here's exactly how I made it work for me:

  1. I downloaded this Xinerama.c file from the Fake Xinerama site.
  2. I opened a terminal, and navigated to the folder folder where I saved Xinerama.c.
  3. I executed:
    gcc -O2 -Wall Xinerama.c -fPIC -o -shared
  4. I opened up nautilus (the gnome file explorer) as root, by typing Alt-F2 and then:
    gksu nautilus
  5. I navigated to /usr/lib, found and made a back up copy of it.
  6. I copied the from my download directory into the /usr/lib directory, overriding the copy there (which I had just backed up in step 5, so I could undo this later if need be.) To keep things clear it was helpful to note that the file size of the "fake" version was bigger (12.6 kb) than the "real" version I was replacing (8.6 kb).
  7. I created a new text file called .fakexinerama in my /home/dave directory and put this in it: (based on my 1440x900 physical screen size)
    0 0 720 900
    720 0 720 900

Fake Xinerama lets you define any kind of virtual screen set up you want, but I just want a vertical split screen. To achieve that on your monitor, X by Y pixels in size, looking at my file example, just replace 720 with X/2 and replace 900 with Y.

That's it. I logged out and back in, and was up and running.

Thanks again to Lubos Lunak for creating this mod and to akira for pointing me at it.

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This helped me out a lot with a three head display. Xinerama is pretty slow with three desktop so using this allowed me to put two of them in twinview without the annoying maximize to both issue and have the third as a separate X screen joined to the twinview with Xinerama. Thanks for taking the time to write out the steps David! – Kyle Brandt Jul 4 '10 at 15:17
Links are broken. – Unsigned Apr 12 at 17:28

There is now a new project called FakeXRandR that works really straight forward.

This is a tool to cheat an X11 server to believe that there are more monitors than there actually are. It hooks into libXRandR and libXinerama and replaces certain, configurable monitor configurations with multiple virtual monitors. A tool that comes with this package can be used to configure how monitors are split.

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I came across an article on omgubuntu that gives a pretty easy way to mimic the Windows Snap functionality in Ubuntu/Gnome using the Compiz control panel. This Windows Snap leaves me with one widescreen desktop, but windows themselves can be easily docked to fill either half screen. (That's not exactly what I was looking for originally, but still pretty handy.)

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I have been using a solution to this exact questions for quite some years using a triplehead2go. That device will merge up to 3 monitors and report one huge monitor to X.

Here is how to split that huge monitor into virtual workspaces in xorg.conf:

Section "Device"
    # ... your other settings above
    Option         "TwinViewXineramaInfoOverride" "1280x1024+0+0, 1280x1024+1280+1, 1280x1024+2560+0"

And if you are using the latest nvidia drivers, those drivers provide their own xinerama extension which seems to ignore the above setting so you must add the following in that device section:

Option         "NoTwinViewXineramaInfo" "true"
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I'm fairly sure you can do this by tweaking your X config file, but I wouldn't just because I'd probably break my display config. If you try this, be very careful, backup you display config & make sure you have an alternative login you can use in case you have to fix your display.

You might get more satisfaction out of a tiling window manager like xmonad, or even running compiz to control how windows open, close & tile.

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Works well for me:

I used the following for two monitors (1280x1024 + 2048x1152):

0 0 1280 1024
1280 0 1024 1152
2304 0 1024 1152
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If you're using compiz you may find its grid plugin an easier and more flexible solution. You can configure it to tile a window over the left/right half of the screen when dragging it against the edge.

That is the Window Snapping feature described in the article David links to. Moreover you can configure shortcuts and make a window occupy the top/bottom half or a quarter of the screen.

Xinerama causes a notable performance hit (since it replicates X actions across all the Xinerama screens) and doesn't work well with composite window managers.

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