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On my laptop using 12.04 I would like to have two virtual desktops, one should be visable only to the person using the computer and the other should be the one that is shown when I attach an external device. At the moment I use the "mirror display" (not sure about the english name for it) functionallity or the "not mirror display" option, but with different virtual desktops it would be nice to set up the "external monitor" before and afterwards look at some notes while giving talks etc.

How can I ajust the settings to achieve this?

Saw a lot of old questions, but no real solution. Maybe this got better with Precise multi-monitor support.

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So, you are basically using "Display" settings, right? With that, you can have two separate desktops already. What else do you need? – Qwerty May 16 '12 at 20:54

On my laptop I was able to do this as follows:

Go to Dash Home and type Displays and select the Displays control panel.

Plug in the external monitor.

Turn off mirroring. You should see two screens depicted in the control panel display.

Select the external monitor's box, move it to the orientation you would like, turn the external monitor on with the panel's on/off control, set its resolution, and then press Apply. They should both blank for a second or two and then come on.

I use Unity 3d and was unable to put them side by side as the sum of the two widths exceeded 2048 (my Laptop is pretty wide compared to how tall it is.) I simply positioned the second display under the first, set a resolution for it and turned it on (with mirroring off, of course), and it came up properly as above. I was able to move back and forth between screens by moving my cursor down off my laptop desktop and onto the external monitor desktop. Just drag the presentation or other window down to put it on the external monitor.

I suppose I could have also switched to Unity 2d instead of putting one screen under the other in the virtual desktop, but I don't see what difference it makes.

The command line program to do this sort of thing is xrandr. I've used that command to put together a little shell script I would it run when I connected to an external monitor to set the second screens's resolution properly and activate it. I put a shortcut on my desktop for it so I wouldn't have to make my audience wait. The particular xrandr options are --right-of --left-of --above and --below.

xrandr --output VGA-0 --mode 1280x1024

xrandr --output VGA-0 --below LVDS

xrandr --output LVDS --mode 1440x900

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I know the "Displays" option and it works quite nice, but what I want is something different. 1. Have 2 virtual desktops 2. Set up one virtual desktop with things I want to show 3. Plug in external monitor and have the prepared virtual desktop shown on the external monitor (and only this desktop no matter if I change desktops on the laptop) – joschi May 18 '12 at 12:14
With 2 monitors displaying two viewports on 1 virtual desktop you can move your mouse pointer from one to the other to control the windows in each. If they were two separate virtual desktops you would need two mice, I would think. That would be like a multi-headed Unix machine. See for something like that--it would require not just two mice and keyboards, but two graphics engines, too. It's likely I'm not understanding you, and if so, I'm sorry. – John S Gruber May 19 '12 at 1:33
I just would like to tell my laptop "Please use Virtual Desktop number x to be shown on the external monitor" when having several of them. – joschi May 19 '12 at 13:17

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