Control monitor to be used

[tony]

Hello,
I am sure there has been lot of forums with similar question. I couldn't 
find answer for what I am trying to do.

  I have one external monitor connected to laptop using VGA.The setup 
works fine as an extended monitor. I want to control the monitor 
application's graphical interface is started. Both the monitors comes up 
as Screen0 and $DISPLAY=:0.0.

Eg:
xclock -display :0.1
Error: Can't open display: :0.1

Does anybody know how can I do it please? I am told "devilspie" can be 
used for the purpose. Although, I am experimenting with ubuntu laptop, 
the method is eventually to be used for an embedded devices. So I would 
prefer to avoid any new application, unless that is the only way.

I noticed, in Ubuntu (12.04, gnome-classic) any application with 
graphical interface once started, is displayed in the monitor where 
mouse pointer resides. I am after the exact method. But not sure how.
Thank you in advance for any suggestions.

Following is my xrandr output (My laptop does not have a 
/etc/X11/xorg.conf )

xrandr
Screen 0: minimum 320 x 200, current 3840 x 1080, maximum 32767 x 32767
LVDS1 connected 1920x1080+1920+0 (normal left inverted right x axis y 
axis) 344mm x 194mm
    1920x1080      60.0*+   59.9
    1680x1050      60.0     59.9
    1600x1024      60.2
    1400x1050      60.0
    1280x1024      60.0
    1440x900       59.9
    1280x960       60.0
    1360x768       59.8     60.0
    1152x864       60.0
    1024x768       60.0
    800x600        60.3     56.2
    640x480        59.9
VGA1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 
531mm x 299mm
    1920x1080      60.0*+
    1680x1050      60.0
    1600x900       60.0
    1280x1024      75.0     60.0
    1440x900       59.9
    1280x800       59.8
    1152x864       75.0
    1280x720       60.0
    1024x768       75.1     70.1     60.0
    832x624        74.6
    800x600        72.2     75.0     60.3     56.2
    640x480        72.8     75.0     66.7     60.0
    720x400        70.1

Thanks,
Tony