keyboard in context menus

Hi,

my application creates context menus with FXMenuPane when a list item is 
right-clicked, like so:

     FXMenuPane pane(this);
     new FXMenuCommand(&pane, "&Foo", nullptr, this, ID_FOO);
     new FXMenuCommand(&pane, "&Bar", nullptr, this, ID_BAR);
     pane.create();
     pane.popup(nullptr, event->root_x, event->root_y);
     getApp()->runModalWhileShown(&pane);

This works as long as I select the menu items with the mouse, and the 
menu can be closed by clicking out of bounds. However, there is no 
keyboard navigation. I can neither navigate the menu with the arrow 
keys, nur can I use the F and B accelerators, or close the menu with 
ESC. Pressing any key results in an application beep. How can I fix this?

And in a related question, what is the fxkeys.h constant for the menu 
key (or application key) on a Windows keyboard? The one that opens 
context menus, and was introduced with the Windows keys. It's not 
KEY_Menu, that one seems to be from some legacy keyboard.

Enno.