tab panel: add ARIA selected property to the currently selected tab title

[becky]

One page tab is actually always selected, even if none of the tabs has focus. The curernt thinking is that the page tab for the visible page should always have the Selected state. The Focused state should be used for when focus is actually on the tab. It would be nice for JAWS to announce that a specific tab is selected even when it is reading with the virtual cursor.

[becky]

In the latest ARIA specification there is currently no selected state assigned to the tab nor tabpanel role. I sent an email to the W3C WAI PF working group (owners of ARIA spec.) for clarification.

[becky]

implementation notes: Firefox 3 will compute the selected state for the tab automatically, as long as something in the tab has focus, and aria-labelledby is used to tie the tabpanel to the tab.

Dojo needs to do container navigation in two steps: 1) If an arrow key is pressed, set focus 2) If a tab is focused, make its tab panel appear

[becky]

Not planning to rearchitect the tab title so that its onfocus handler does the hide/show of the tab panel - we have the stack controller for that and currently the title button knows nothing about the other tab components.

[12280] closes #3945 and refs this ticket. labelledby property has been added to the tab panel but is still not working correctly with FF3 so may need additional changes.

[becky]

Looks like Dojo changes are correct but there are the following Firefox 3 bugs that are related: *https://bugzilla.mozilla.org/show_bug.cgi?id=397800 *https://bugzilla.mozilla.org/show_bug.cgi?id=417859 - No focus event on item focusable because of overflow when role="presentation"

Although generally items with role=Presentation should not receive focus.