Hi,

This patch tries to fix height calculation for menu bar in X when not
using a toolkit.  It is taking into account the fact that the menu bar
face could be boxed.

There are others issues left (i.e. not handled by this patch):

      - a customization of the menu face does not trigger a redisplay,
        so one has to deactivate/re-activate the menu bar in order to
        update (I don't know how this is done for other faces)
        
      - with a boxed menu bar face, the box is not displayed correctly
        on the right side of the bar