Comment 12 for bug 1774046

The more I look into this, the more it looks like something you need to report to Xubuntu. For some reason, garcon is not loading the /usr/share/applications/Thunar.desktop file, which means that Whisker Menu doesn't see Thunar.

That isn't the way things are configured by Xfce as far as I can tell, so I think Xubuntu must have changed something. In Arch Linux it sees that file, so when I search I find "Thunar File Manager". I also see it under "System", which is where it would show up if it was loading the .desktop file.

I don't think there is anything I can do, sorry.