topmenu hooks the standard GTK+ menu system, as a menubar plugin for LXDE, Mate, and a couple of others. There is also components for QT and GTK3, requires seperate compiled binary, and they are not as "fully functioning" as the gtk module, but they work.
Visibility wise TopMenu places the window menu and the About submenu as submenus off a root menu item (in bold) that contains the name of the App. This can be easily hacked out.
I use topmenu-gtk on Raspbian Jessie, with only one modification, the version that gets checked for lx-menu needs to be dropped from 7 to 6. v0.6.2 is donkeys old, but Jessie builds do not include v0.7.0, With that change it works fine "out of the box". you may also have to manually check and change the destination of the lx-menu headers (Raspbian moves a ton of stuff into /usr/lib/arm-...)
NOTE: undocumented (or badly documented) standard functions of an LXDE Menu button config allow you to create an Atari style (pre) menu item, like the one that contains the accessories. I found the correct commands by accident while searching for something else to do with LXDE menu config files, I'll edit this post with the correct info when I get access to my Raspbian Jessie machine.
topmenu-gtk is available of some platforms, like Linux Mint Mate (also works with LXDE) and will compile on most linux systems with either v0.6.2+ or v0.7.0+ of LXDE/lx-menu, Mate, and one other menu bar manager (its mentioned in TopMenu docs)
topmenu-gtk detached menu: https://git.javispedro.com/cgit/topmenu-gtk.git/about/
Openbox Atari Theme: https://www.box-look.org/p/1017525/
google AtariST8x16systemfont.ttf : http://www.google.com/search?q=AtariST8 ... emfont.ttf
Atari ST console font (big and small): http://www.modelb.bbcmicro.com/retro-fonts.html
Atari ST mouse (~/.icons): http://www.atari-forum.com/download/file.php?id=22272
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