@weaver.
I can see that options in +Xtreme Plus > Smart menu page, under Option for Extra Menu,
But this only appears to work with the Extra menu style, and therefore cannot change the primary or secondary menu bars.
Am I missing something ?
If I am not, may be you could generalize the option (in Plus) by adding that option in Main options > Menus, In the Smart menu box below the threshold box, so it would apply to ALL menus.