Drop-down menus trap tab-focus...

The quick search in the top menu opens a drop-down list of suggestions. These suggestions use the tab key for navigation, which prevents users from moving beyond the suggestion dialog to (for example) the help menu.

Users who are logged in will automatically see recently viewed pages and immediately encounter this problem.

The same is true of the help and user profile menus, although those do not automatically open.

The preferred behavior is to use the arrow keys to navigate within the list and reserve the tab key for moving into and out of the parent menu.

This is a requirement to meet Level AA of the WCAG 2.0 standard.