Check out this link on thinkwiki.org using xrandr to assign different applications on different monitors.
[http://www.thinkwiki.org/wiki/Xorg_RandR_1.2#Using_.24_xrandr
[b]
X RandR is used to configure which display ports are enabled (e.g. LCD, VGA and DVI), and to configure display modes and properties such as orientation, reflection and DPI.
It is possible to set screen locations as –left-of, –right-of, –above and –below. Assuming displays sizes of 1024x768 and 1200x1600:](http://www.thinkwiki.org/wiki/Xorg_RandR_1.2#Using_.24_xrandr)
$ xrandr --output LVDS --auto --output VGA --auto --right-of LVDS
and
$ xrandr --output LVDS --mode 1024x768 --pos 0x0 --output VGA --mode 1600x1200 --pos 1024x0
](http://www.thinkwiki.org/wiki/Xorg_RandR_1.2#Using_.24_xrandr)are equivalent. Both will place the external monitor to the right of the laptop display within the virtual screen.
If the Virtual size is only 2048 wide the above command will fail as the combined width of the two displays exceeds the maximum virtual size.
However it is possible to have overlap the display viewports. So to fit within the 2048 limit:
$ xrandr --output VGA --mode 1024x768 --pos 0x0 --output VGA --mode 1600x1200 --pos 448x0
[Xrandr is used to set the size, orientation and/or reflection of the outputs for a screen. It can also set the screen size.
If invoked without any option, it will dump the state of the outputs, showing the existing modes for each of them, with a '+' after the preferred modes
and a '*' after the current mode.
There are a few global options. Other options modify the last output that is specified in earlier parameters in the command line. Multiple outputs may be
modified at the same time by passing multiple --output options followed immediately by their corresponding modifying options.
--help Print out a summary of the usage and exit.
-v, --version
Print out the RandR version reported by the X server and exit.
--verbose
Causes xrandr to be more verbose. When used with -q (or without other options), xrandr will display more information about the server state. Please
note that the gamma and brightness informations are only approximations of the complete color profile stored in the server. When used along with
options that reconfigure the system, progress will be reported while executing the configuration changes.
-q, --query
When this option is present, or when no configuration changes are requested, xrandr will display the current state of the system.
--dryrun
Performs all the actions specified except that no changes are made.
--nograb
Apply the modifications without grabbing the screen. It avoids to block other applications during the update but it might also cause some applica-
tions that detect screen resize to receive old values.
-d, --display name
This option selects the X display to use. Note this refers to the X screen abstraction, not the monitor (or output).
--screen snum
This option selects which screen to manipulate. Note this refers to the X screen abstraction, not the monitor (or output).](http://www.thinkwiki.org/wiki/Xorg_RandR_1.2#Using_.24_xrandr)