Sorry if these have already bee suggested.
I think it would be excellent if you could incorporate a way to extend the menu background across the width of the containing space. As you suggested to me back in May (sorry for not acknowledging that post, by the way,) this is possible by creating a background graphic, putting the generated menu in a div, setting the background image to the one created for that, and setting the div width to 100%. I think the program should be able to do that for us.
Also, where button size is concerned, you can currently go Auto or set height and width manually. There should be the option to go mixed auto and manual. I might, for instance, want the menu buttons precisely 30 pixels high, but the width to auto size on the text of the button. Or (although probably a far less common scenario) I might want 80 pixel wide buttons, but the height to size according to the text size.
Thanks for a great product so far...