using visiblebindingvalue with menu

I'm keying visibleBindingValue off of a menu and seem to be getting strange behavior. If the menu item I specify in the binding is selected, the field appears as expected. If one of the menu items (other than the one I specify in the binding), the field does not appear, as expected. However, when the configUI first appears, and no menu item has yet been selected, the field appears - this was unexpected. Could this be because, before the user selects a menu item, the menu effectively contains all of the choices and therefore it matches my binding? Is there any way around this?

[jay (support)]

Specifying a default will solve the problem.