Hi Adrian,
We’re working on adding direct support for hamburger menus (a menu bar that is replaced by a hamburger menu on narrow screens), but this won’t (initially at least) include submenus.
It’s also possible to use markup to add a hamburger menu in the current version of Xway.
My general impression is that drop-down (Mac-style) website menus are less common now than they were in the past (15 to 20 years ago), and I don’t find them particularly helpful. I think there’s a difference between drop-down menus in an app (which you might use frequently and which follows standard conventions) and drop-down menus in a website (which you might not visit very often). People will invest more time in learning an app than in learning a website.
My own preference is for a website to have a top-level navigation bar (without submenus) and to include further links on the target pages. I find that clearer and less intimidating, and it’s the approach that Apple use on their website. Our own website (softpress.com) also follows this approach.