Some recent ubuntu-based upgrades are now missing gksu, used to auto-start root-based operations from terminals or shortcuts. In particular, a newly installed Lubuntu would not let me launch files and folders from thunar (I replace pcmanfm, which I have never taken to).

Solutions I've found include:
sudo -H thunar %f (folders)
sudo -H geany %f (files)
thunar admin://%f
geany admin://%f

Although these work in Terminal, none work for thunar "launch as root".

pkexec and policykit have been suggested but are not available for Lubuntu, so that's another option closed.

Anyone else come across this problem and solved it?