I noticed that though Trisquel has the "add printer" feature, it always gives
an error.
I tried running "hp-setup" but it also failed.
The solution was to run it as sudo. So my point is, the "add printer" feature
should issue a request for the sudo password (just like synaptic or gparted)
to be able to add the password.
Should I file a bug for this? Or has it been discussed before and it's not
possible to fix?
I only knew of the sudo hp-setup because I had it in Debian, but for most
people this would be a real PITA.