Some apps will not load in VNC, why?

[Bijan Soleymani]

On 2022-01-26 12:17 p.m., Bo Berglund wrote:
> If this is the case, what is the solution?

The solution is to run mate-polkit or an equivalent polkit 
authentication agent:
https://wiki.archlinux.org/title/Polkit#Authentication_agents

The issue with mate-polkit if you are hitting the same bug as I sent, is 
that the program is not compatible with /proc being mounted with the 
hidepid option. So if you want to use that program change the settings 
for how /proc gets mounted.

https://linux-audit.com/linux-system-hardening-adding-hidepid-to-proc/


> If "session" is connected to some property of the desktop, then it should grab
> the VNC desktop which is what is running and where the request to show the app
> (GParted for example) comes from.

If you are getting the same error as the bug I posted, mate-polkit tries 
to open /proc/1/cgroup

Fails and then you get that unrelated session error. Nothing to do with 
sessions.

> If it tries any other (physical) desktop then there is none in this case AFAICT.

See last point below.

> The behaviour when starting GParted in VNC is to show a circular mouse pointer
> that rotates, probably a timeout of some kind. After a while it disappears and
> nothing else happens.

Is this from the command line or from the menu.

Without polkit agent running I get:
gparted
Error executing command as another user: No authentication agent found.

> If I start GParted in the physicak computer desktop then a pop-up dialog is
> shown where I am asked to enter the sudo password. This stays on indefinitely so
> there seems to be no timeout. When pwd is entered GParted loads normally.

I would check if any of the agents listed on the above wiki are running:
ps -ef | grep polkit
root        1237       1  0 Jan24 ?        00:00:04 
/usr/lib/policykit-1/polkitd --no-debug
bijan     161243       1  0 14:04 pts/3    00:00:00 
/usr/lib/x86_64-linux-gnu/polkit-mate/polkit-mate-authentication-agent-1
bijan     161251  154251  0 14:05 pts/3    00:00:00 grep --color=auto polkit

It might be that the agent is running for the desktop session. It tries 
to open a popup on the non logged in desktop and fails and gparted fails 
afterwards.

Also try the same thing in the VNC while there is a user logged in to 
see if the password dialog appears on that desktop.

For me if I run mate-polkit on vnc :1 and then log in to vnc :2 and run 
gparted then the password dialog appears on :1 and not :2

Bijan