This test starts with the keyboard accessible version from http://carroll.org.uk/sandbox/suckerfish/bones2.html and adds code from http://qrayg.com/learn/code/cssmenus/ to make it look prettier.

Keyboard accessibility works in FF2, FF3, IE6, IE7, and Opera 9.5 for Windows.

Dropdowns & hovers work in FF2, IE6, IE7, Safari for Windows.

In FF3, when you roll over any of the top-level menus, the secondary menus appear as expected. However, when you try to click on anything in the nested secondary menu, it only works sporadically. Sometimes it works perfectly, but sometimes it disappears too fast for me to click on it. The hover doesn't always persist, but I can't figure out the pattern for when it works or doesn't.

In Opera 9.5 for Windows, I have the same problem as in FF3. Nested menus are visible but not always "sticky," so you can't click on anything in them. Keyboard access works with Ctrl+Down, not Tab.