Comment 5 for bug 565305

Those interested, I posted a workaround on my bug report. I will post here so you can work in the meantime!
using the following script in /etc/X11/Xsession.d/45custom_xrandr_settings:
Code:

EXTERNAL_OUTPUT="VGA1"
INTERNAL_OUTPUT="LVDS1"

xrandr |grep $EXTERNAL_OUTPUT | grep " connected "
if [ $? -eq 0 ]; then
    xrandr --output $INTERNAL_OUTPUT --off --output $EXTERNAL_OUTPUT --auto
else
    xrandr --output $INTERNAL_OUTPUT --auto --output $EXTERNAL_OUTPUT --off
fi

What the script does is disable my LVDS display when I connect the external monitor.