I have the same problem. Tried settings with Jupiter and I can not get to the bottom of the screen. Same thing with xrandr,
using these lines from terminal re-sizes the screen but again the mouse will not move to the bottom.
xrandr --output LVDS1 --mode "1024x600" --scale "1x1"
xrandr --output LVDS1 --mode "1024x600" --scale "1x1.28" will get scale to 1024x768
I was running Peppermint until a few days ago and had the same problem, that particular fix did not work here though. It had to do with a patched xserver-common. I have found a lot of references to the problem but no solution. Did you manage to solve it?