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Re: accessible tree menus

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From: Steve Green
Date: Feb 23, 2009 3:30PM

In our experience of user testing, expandable menus always cause problems
for screen reader users. This is predominantly because they are only ever at
a single point on a page and don't have a good holistic view of it. It is
very difficult to build and maintain a mental model of the tree as it
changes. Furthermore, the only relevant semantic structure is a nested list,
and this is usually quite incomprehensible to a screen reader user because
there is far too much information to remember.

For instance they know where an 'expand' node is but they don't know how
much content has been revealed when the node is expanded. They only know
where the start of it is.

If it is only one level of nesting, they may well be able to cope, but we
have seen menus with more than ten levels of nesting and hundreds of nodes,
and this is quite impossible to navigate sensibly.

The worst examples are where only one node can be open at a time, so opening
a new one automatically closes the last one. Screen reader users are totally
unaware that this has happened so they cannot find menu items they found
before.

Steve