Hi, I had the same problem on XFCE in Debian testing. I did some searching of the original repo's README and discovered there are a few settings that have to be flipped in XFCE on Debian. Based on similar settings existing for MATE, I'd assume the same is true there, and, finally, also for Budgie (but that's not an official Debian DE so I'm not worrying about it).
For XFCE: xfconf-query -c xsettings -p /Gtk/ShellShowsMenubar -n -t bool -s true xfconf-query -c xsettings -p /Gtk/ShellShowsAppmenu -n -t bool -s true For MATE: gsettings set org.mate.interface gtk-shell-shows-app-menu true gsettings set org.mate.interface gtk-shell-shows-menubar true The original information and README are [here](https://gitlab.com/vala-panel-project/vala-panel-appmenu/blob/master/README.md). The information about `appmenu-gtk-module' seems not to be relevant to Debian as the changes it makes seem to be in the install scripts already. I have fixed the problem on XFCE by adding a file in the `/debian' direction called `xfce4-appmenu-plugin.sh' with the above commands. I also made one for MATE (`debian/mate-applet-appmenu.sh') that presumably works, but I am not sure since I'm running XFCE. I can't find information on exactly how to submit the actual source changes, so I'm hoping this is the correct way to report fixes. If not, let me know and I'll happily do things properly. Regards, JTS
