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http://www.webupd8.org/2012/01/hud-ubuntus-new-smart-menus-a...
I'm still not sold, I found the UL-Corner positioning greatly aggressive. I'd put it in the bottom personally but I'm used to the Unix 'bottom command line' habit.
Otherwise it's one step closer to a contemporary desktop command line, in the video the guy even typed 'undo' in inkscape, made me smile. I guess having this common iterative search of nested menus will greatly help users, as it helped many of us in the shell or emacs (or any system providing this idea)