With a little more experimenting, I discovered (as stated in another thread), that submenu buttons will open in available space. Since I wasn't quite sure what that meant, I mistakenly thought I wouldn't be able to see the submenus in my Menubutton width HTML frame. What actually happens is, the submenu will open on a layer over the main menubuttons. Subsequent sub/submenus open over the submens and so on. Bottom line, it all fits nicely in the menubutton frame. Hopefully this will help others who may be as confused as I.