Comment 9 for bug 1212704

I'm not sure how to do it via the Displays configuration, but have provided the xrandr output above. If the two monitors overlap in anyway without it being a perfect overlap the error is thrown.

I normally use arandr for display configuration.

If I open the Display configuration option under XFCE Settings Manager, I do not have the option to mirror to displays of different sizes. However, I do have the option to set the position as "Same as". The net effect of this is shown in the following xrandr output:

$ xrandr
Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 16384 x 16384
VGA-0 connected 1280x1024+0+0 (normal left inverted right x axis y axis) 376mm x 301mm
   1280x1024 60.0*+ 76.0 75.0 72.0
   1152x864 75.0
   1024x768 75.0 70.1 60.0
   800x600 75.0 72.2 60.3
   640x480 75.0 72.8 59.9
   640x350 70.1
LVDS-0 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 344mm x 193mm
   1920x1080 60.0*+ 50.0
DP-0 disconnected (normal left inverted right x axis y axis)
DP-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
DP-3 disconnected (normal left inverted right x axis y axis)
DP-4 disconnected (normal left inverted right x axis y axis)
DP-5 disconnected (normal left inverted right x axis y axis)

From the above you can see that both screens have different resolutions. The VGA-0 display is 1280x1024, while the LVDS-0 display is 1920x1080. However, both screens are positioned to start at 0x0. The result of this is that the two screens both display the same content for the 1280x1024 region.

This configuration causes the aforementioned error from spicec but not spicy:

$ spicec -h 127.0.0.1 -p 5900
Error: unhandled exception: unsupported partial overlap

$ spicy -h 127.0.0.1 -p 5900
GSpice-Message: main channel: opened

I'm also attaching a screen shot of the arandr display for this screen configuration