General :: How To Disable Other Monitors While Running Games In Wine

My current setup is:
* Dual GTS 250 video cards
* 3 Monitors
* Used nvidia-settings to run each monitor as a separate x session
* This is all running on Linux Mint Debian Edition

When running games (Starcraft II) in Wine via PlayOnLinux, I've found that the mouse does not get locked. I already tried various solutions littered across the web and none work so I'd rather just disable my other two monitors while playing. Does anyone know of a method where I can turn off my other two monitors (not my primary monitor) while running Wine and then turn then back on afterwards? I don't mind having to manually run a script before and after gaming.

This is the output of my xrandr for each of my monitors (I get a different xrandr depending on which X session (i.e. monitor) I try xrandr on):
Primary Monitor
xrandr: Failed to get size of gamma for output default
Screen 0: minimum 320 x 175, current 1920 x 1080, maximum 1920 x 1080
default connected 1920x1080+0+0 0mm x 0mm .....

Second Monitor
xrandr: Failed to get size of gamma for output default
Screen 1: minimum 320 x 240, current 1280 x 1024, maximum 1280 x 1024
default connected 1280x1024+0+0 0mm x 0mm .....

Third Monitor
xrandr: Failed to get size of gamma for output default
Screen 2: minimum 320 x 175, current 1280 x 1024, maximum 1280 x 1024
default connected 1280x1024+0+0 0mm x 0mm .....

I could not figure out from the above outputs what I should be using for the --output flag. I assumed it was default and tried the following:
~ $ xrandr --output default --off
xrandr: Failed to get size of gamma for output default
But as you can see, it didn't work. Additionally, since all three xrandr outputs list the monitor as default, I wouldn't know how to turn my other monitors back on afterwards (if the command did work). Do you know what might be wrong in my nvidia-settings or what else I could try?