Yes, I understand....
anyway I solved the problem

1: Do NOT use Alacarte
2: Delete /home/knoppix/menus/*
3: Delete /home/knoppix/.config/menus/*
4: Create new menu category called "Hidden Gems" in /etc/xdg/menus/applications-merged/ (copying & editing for example knoppix.menu to learn the correct syntax)
5: Create new items called "XKill" for the "Hidden Gems" menu just created putting Xkill.desktop file in /home/knoppix/.local/share/applications/ (copying & editing other .desktop file to see the correct options) and so on for other items
6: In a terminal:
Code:
root@Black:/home/knoppix# xdg-desktop-menu forceupdate  #I don't know if it's necessary
Take a look to explore the topic:
http://standards.freedesktop.org/des...y-spec/latest/
http://portland.freedesktop.org/xdg-...ktop-menu.html