Hello,
when you try to start gparted and nothing happens, this might help.
Running from terminal i saw this message:
$ gparted-pkexec
/var/lib/polkit-1/localauthority/90-mandatory.d does not exist. Please install policykit-1
But policykit-1 is installed, of course.
The solution is another nice finding of our user terroreek. Please execute as root:
# mkdir -p /var/lib/polkit-1/localauthority/90-mandatory.d/
This will enable gparted to create the file /var/lib/polkit-1/localauthority/90-mandatory.d/udisks2-inhibit.pkla while it is running.
greetings
musca