The scenario is: Once you have "used" contextmenu just one time (that is, you have right-clicked on a folder or message), keyboard_shortcuts does not respond anymore to any key.
I can reproduce this. Although context_menus isnt mine, i'll have a look at it.
Another issue with keyboard_shortcuts (not related to contextmenu) is that if you press the "?" key to display the shortcut help, all of a sudden vertical and horizontal scrollbars do appear and cause a sort of "flicker" because of the screen redraw. And there are some missing strings, but that's a minor issue. All in all, keyboard_shortcuts looks a bit outdated. I've disabled it for now.
This I cant reproduce. What browser?
Cor