Tray Icon not Properly Displaying

[RayJW]

For some reason, the tray icon doesn't work for the Flatpak, and it simply displays three dots. While I've had a few apps doing that in the past, it's usually been Electron applications that didn't set the TMPDIR correctly (like with the Discord Flatpak), but Lutris is now the only app out of many that is causing issues. I saw this issue, and I think this might be related, since the icon that Lutris installs is correctly called net.lutris.Lutris, so it probably wouldn't be detected if the application ID is set to lutris. Sadly, I found no easy way whatsoever how to check the application ID of a running application in GNOME, and the icon seems to work fine in other locations. There are multiple issues reported with extension, but none of these seem to apply to Lutris in my understanding.

I also found this issue with Solaar which at least would be a GTK application, so closer to Lutris. But from what I understand, this Flatpak already correctly packages the libappindicator-gtk3 requirement.

The same is happening on the beta branch of Lutris, since apparently the tray icon implementation changed, but that has the same problem for me. I checked all the logs, but there is absolutely nothing related in either the Lutris logs when running in the terminal or the gnome-shell logs where the icon issues with Electron apps produced an error.

Edit: out of curiosity, I tried building the beta branch with the libayatana-appindicator-gtk3.json submodule instead of the libappindicator-gtk3-introspection-12.10.json one. While this is a change that should probably be made any way as this is the better implementation of the two, this didn't fix the issue. So the upstream change to support libayatana-appindicator didn't help with this. At least that probably narrows it down to most likely being an issue with the path where the icon is being looked for, as I initially suspected.

Edit: I just checked with Sway and Cosmic. I can confirm, that the same is happening with all three DEs. So this must be more far-reaching than merely an issue with the GNOME extension.

[RayJW]

I narrowed the issue down, and the problem is definitely the Application ID. The Flatpak exports the icons in ~/.local/share/flatpak/exports/share/icons/hicolor as net.lutris.Lutris. The issue is, that the AppIndicator has the application most likely set to lutris (might happen somewhere around here). I think the best fix would be to use the reverse domain naming scheme upstream as well. However, if that is not desired one could fix this with some hacky workarounds as can be seen here.

This can be confirmed by renaming the appropriate net.lutris.Lutris.png to simply lutris.png (in my case 16x16), after which the tray icon will work as expected.