Hi , I had same problem and here is a workaround that worked with my install (MacBook air, Parallels 9 (last fix), Mint 17 Cinnamon).
After install Mint 17, I got the message after 1st login : "Software running in rendering mode" => to solve this, just re-install Parallels Tools (boot VM, go to Menu "Virtual Machine" and "Install Parallels Tools".
The for changing resolution , let's say 1024x768 (or like me for the 13' MBA : 1440x900) :
edit the default grub cfg file :
#sudo vim /etc/default/grub
change, uncomment, or add:
GRUB_GFXMODE=1024x768
GRUB_GFXPAYLOAD_LINUX=1024x768
update grub:
#sudo update-grub
reboot !