possible focus trap

[pkra]

I saw an instance where a nested link led to a focus trap (on Chrome but not Firefox). Needs investigation.

[pkra]

This is particular to the MathJax examples. Here's what I think is happening.

• we enter a tree with a link in a treeitem.
• while there's a link later in the taborder, we hit TAB
• since anchors are in the taborder, they are focused
• a focusin event is triggered for the current tree
• tree-walker looks up last active node and puts that into focus

I see this Chrome, FF, WebKit now that I understand it.

On the one hand, it's luckily not a complete trap since the last link will allow TABbing out (for AT users, focus can move past the tree in browse mode anyway).

But this needs fixing.

More generally, we should probably check if focus is moved to somewhere in the tree (e.g., a deep link) in which case we might want to resume navigation from the nearest tree item.

[pkra]

The quick and dirty solution would be to remove anchors in the tree from the taborder. If the link is a tree item, it can be reached. Otherwise, it's probably not really a tree.

[pkra]

More generally, we should probably check if focus is moved to somewhere in the tree (e.g., a deep link) in which case we might want to resume navigation from the nearest tree item.

Note to self. FF doesn't seem to focus correctly, Chrome does seem to.