I still need GKSU for a variety of applications. Or, at least, I want it since the alternatives are, for the moment, less than convenient. So, I have found the following solution that works for me. I have not detected any unforeseen issues as of yet (I have been running it for a few days now). But, if you decide to do this for yourself, you must accept full responsibility and so should not execute the following commands if you are unsure what you are doing.
Anyway, the above, said, here is how to reinstate GKSU:
Add artful repositories to the system
cat <<EOF | sudo tee /etc/apt/sources.list.d/artful.list
deb http://archive.ubuntu.com/ubuntu/ artful main universe
deb-src http://archive.ubuntu.com/ubuntu/ artful main universe
EOF
Update package cache
sudo apt-get update
Install necessary build tools
sudo apt-get install build-essential debhelper dpkg-dev
Install build-dependencies for gksu and compile its source package
sudo apt-get build-dep gksu
sudo apt-get source --compile gksu
Install self-compiled gksu packages:
sudo apt-get install ./*gksu*.deb
Test gksu (should work on Xorg-sessions)
gksu-properties # check that it has "Authentication mode" to "sudo"
gksu date
gksudo date
Remove artful repository from system for safety
sudo rm /etc/apt/sources.list.d/artful.list
sudo apt-get update
Original source for the above method can be found here: