How to get two monitors working in Linux?

[Aaron Plattner]

On 12/27/2011 06:34 PM, monitorxxx wrote:
> Hi, I have Arch Linux in this system:
>
> -video card: nvidia 6150
> -monitor 1: LG, 1440x900 (right side)
> -monitor 2: Samsung, 1360x760 (left side)
> -desktop environment: Lxde
>
> But the problem is that:
>
> 1) no matter how hard I try, write to xorg.conf, set up and reboot, the
> monitors' positions are always changed in NVIDIA X Server Settings (the
> graphical tool).

Does the physical position of the screens swap too?  I.e., does the 
blank monitor change when you restart X?

There was a bug fixed in version 290.10 of the driver that would cause 
displays to get swapped when restarting X servers, but it should have 
only affected secondary GPUs.

The nvidia-settings control panel may not show the correct positions of 
the screens in separate X screen mode because the X server doesn't 
provide a way for X clients to know their relative positions.  My patch 
to fix it ballooned into a much larger change during code review and I 
never got around to finishing it.

> 2) the screen now (Lxde) is shown in monitor 1 (ok), but monitor 2 is
> completely black  and when I put the mouse cursor there, it changes to the
> defauld Gnome mouse cursor (the 'X') and when clicking with the right button
> anywhere in the screen (of monitor 2) nothing happens.
>
> I want both monitors running the same Desktop Environment (in this case,
> Lxde), with "separate screens" and when a program is executed in one screen,
> it does not open in the other. And of course, to be configured in the
> positions they are on the table (Samsung at the left, LG at the right).

I'm not familiar with LXDE, but desktop environments have recently been 
losing proper support for multiple X screens.  For example, KDE 3 worked 
great with multiple X screens but KDE 4 shows the 
black-screen-and-giant-X-cursor problem you're describing with LXDE.  I 
would suggest contacting LXDE's support community to ask for proper 
multiple X screen support.

Desktop environments aren't the only ones simply ignoring multiple X 
screens.  For example, Chrome has had a bug since at least 2009 that 
prevents you from opening new windows on the correct screens:

http://code.google.com/p/chromium/issues/detail?id=15781

I believe Firefox still has a similar problem, though I haven't tried it 
recently.

> Do you know how to solve this problem?
>
> What additional information or log files do you need?
>
> Thanks!