Looks good, but have you considered making this more useful in the Flatpak version? Users will probably expect the command to run outside the sandbox. You could do this by prepending flatpak-spawn --host -- to the argv of the command when running in the Flatpak environment, which you can detect with if (g_access("/.flatpak-info", F_OK) == 0). Note that this would also need permission to talk to the org.freedesktop.Flatpak D-Bus name.

I had not, I've never really used the flatpak version. Thanks for the pointers on where to start, I'll look into it

I've made the changes I think are needed, but I don't seem to be able to launch vlc when running a flatpack version of HandBrake. Is there something I'm missing with permissions?

@robxnano or @jstebbins Any advice if you have a minute

flatpaks don't have direct access to the hosts applications. I.e. if you run

flatpak run --command=bash fr.handbrake.ghb
ls /usr/bin

you will see a different list of applications than is available in /usr/bin outside of the flatpak.

The flatpak ecosystem provides portals for things like this, but I don't know if there is a portal for execution of arbitrary apps. There is however a portal for launching the default app for a uri, g_app_info_launch_default_for_uri()
See https://docs.flatpak.org/en/latest/portals.html and https://blogs.gnome.org/mclasen/2016/07/08/portals-using-gtk-in-a-flatpak/

Maybe g_app_info_launch() also has this ability to go through the portal, but I doubt it. I could not find any information indicating this would work.

Apologies for dropping the ball with this one, life and all that. I have worked out how to get this to work with flatpak though. I had --system-talk-name instead of --talk-name for the org.freedesktop.Flatpak permission. With that corrected, flatpak spawn --host -- does what it should

I've rebased and fixed the flatpak permissions

I'm not expecting this PR to be merged for 1.9, as it does contain a new string in the Linux UI

Since we are well past 1.9, is this in a state to consider merging?

I think so, I've addressed all the feedback I've received so far

OK, Thank you!