Officially suggested keyboard interaction for sub-menu items in the "navigation"?

Hi everyone,

In order to make sub-menu itmes in the navigation (role="navigation")
keyboard navigable, I was changing them into "menubar", "menu", and
"menuitems" (by using a jQuery
plug-in<http://view.jqueryui.com/menubar/demos/menubar/default.html>)
to add keyboard shortcuts on them.

However, as defined in the spec<http://www.w3.org/WAI/PF/aria-practices/#menu>,
when opening such a sub-menu, vendors should "places focus on the first
menu item". (please see the jQuery page for demo) Maybe that's fine for
assistive technologies to automatically focus the first sub-menu item, but
that is likely to confuse mouse users. For the navigation, the first
sub-menu item shouldn't get focused before mouse users move their mouse
cursor onto it.

That makes me re-think if it is really appropriate to use "menubar",
"menu", and "menuitems" in the navigation.

So if there is officially suggested keyboard interaction specifically for
sub-menus of the "navigation" rather than using the one for "menubar",
"menu", and "menuitems"? If not, wouldn't the above mentioned auto focus
thing confuse mouse users?


Sincerely,
Ian Yang