There are still issues with sudo in the Debian images (And possibly the ubuntu images), while currently I am unable to upload new images in the mean time here is the steps to fixing these errors (and thus letting you using root within the GUI).
If you are using the debian images you will find that sudo is completely left out, so first you will need to install sudo via the command line android terminal app (once debian is booted).
T0 do this type:
apt-get install sudo
Once this is installed everything is the same for either ubuntu or debian, you next need to open the sudoers file:
This will then open in the terminal, move down to the end of the file (you may need to install a keyboard that has arrow keys like this one HERE) and type the following line
for debian type:
debian ALL=(ALL) ALL
for ubuntu type:
ubuntu ALL=(ALL) ALL
Save these changes and reboot your linux install, you should now find that you have root working again in the GUI.
I do plan to of cause release new images with this working ‘out of the box’ but this will allow you to fix it in the mean time.
Any questions feel free to comment here!