I’m on Debian though… and my cure is to install lxqt-sudo (and lxqt-sudo-l10n) without recommends then create a script called gksudo somewhere in my path with this highly complex content:
lxqt-sudo $@
Anything that calls gksudo then just works. Even if the dialogue is headed “LXQt sudo”
There wasn’t until I found this & created the config in the linked thread from there.
Then the logs complained about lvm_create_filesystem_snapshot & it’s remove counterpart being missing, so then I copied those out of the source into their place…
Now it complains instead that it can’t open
/usr/local/share/urbackup/filesystem_snapshot_common
Which unfortunately doesn’t appear to exist anywhere I can find on the installed system or in the extracted source tarball.
From the state of the logs it appears I also need to fix this:
Bug in lin_tokens.cpp - client - UrBackup - Discourse