Doesn't work for me either, but this does:SFR wrote: it apparently works for most of folks, but not for me (with or without <shift>).
Step1: Create file /root/.gtkrc.mine (I didn't have one and the theme changer overwrote my settings in /root/.gtkrc-2.0 and referenced this file. I didn't bother to check how to put it permanently into .gtkrc-2.0)
Step2: Input the line
gtk-menu-bar-accel=F20
I know that the default is F10, but I don't know the syntax. I tried to set it to F12 and other real function keys, but it doesn't work, so I thought I might as well use a dummy key. The important point is: No menus popping up anymore and the Press and Release Events script now accepts F10. It didn't respond before.