Hi, you can use the following API tweak:
$('#main-menu').bind('click.smapi', function(e, item) {
var $item = $(item),
level = $item.parent().parent().dataSM('level'),
$sub = $item.parent().dataSM('sub');
if (level == 1 && $sub && $sub.dataSM('shown-before') && $sub.is(':visible')) {
$(this).smartmenus('menuHideAll');
return false;
}
});
Let me know if you still have any troubles.
Cheers!