Application Menu widget locks up the panel and then the entire desktop if custom xdg menu file cannot be found.
How to reproduce:
- Panel preferences
- Add an Applications Menu item
- Go to the item's configuration. At the bottom there is an option "Use custom menu file."
- Select that option and choose an xdg menu file. For example on Xubuntu, this file will give you a settings menu that has everything found in the settings app: /etc/xdg/xdg-xubuntu/menus/xfce-settings-manager.menu
- Close out all the prefs stuff.
- Rename the menu file you selected, so that the panel can no longer find it.
- Restart the panel.
- Click the Application Menu item you created.
Result:
The following error dialog will be shown:
As long as this dialog is on screen, the rest of the desktop will continue to work. However, as soon as you close it, the panel will grab focus, like it does whenever a menu is open, except it can't open the menu, so you can never escape. You can't click on other windows, or other menus on the panel. You can't interact with anything and must kill the panel from a side shell or simply hard reset the computer.
How I discovered this:
I used xfce4-panel-profiles to export my custom configuration on Ubuntu (which refers to the above file) and then I tried to import it on a Fedora Xfce (Vauxite). Obviously xdg-ubuntu does not exist on any Fedora system, but I forgot it was there.
In any case, this should not crash the entire desktop. Panel should drop its focus grab if opening the menu failed for some reason.