on 03/11/2006 11:18 Barney Carroll said the following:
<snip>
By the way, could anyone elaborate on what tab-indexing is? And how does
the Alt+# system work? These seem to be crucial elements of screen
reader browsing but I have a very limited grasp of their convention and
application.
Tabindexing allow a designer to specify the order in which links or
controls receive focus on a page when using the TAB key to move around.
Elements on a page that do not have an associated tabindex will have a
'natural' ordering (ie follwong the order they appear in the markup). If
you mix the two, the elements with a specified tabindex will come first
followed by unindexed elements.
Speaking as an intermittent keyboard navigator/VR user, I consider
tabindexing to be the spawn of satan - especially when it runs contrary
to the 'natural' or expected tab order on a page.
For example, if I land on a page which renders some content containing a
few links followed by a form, I expect to be able to tab to the links
first followed by the forum controls. One common use of tabindexing that
I come across in this situation gives preference to the form controls
and leaves the links unindexed. So, when I hit the TAB key expecting to
jump to the first link, I actually end up on the form and often have to
tab through the whole thing to get back to the links which, visually,
are actually higher up the page. The end result (especially if there is
a lack of visual highlighting on focus) is often complete
disorientations and exasperation. On really bad pages, I sometimes have
to rely on reading the browser status bar just to try and figure out
where I'm tabbing to!
If I had one thing (OK- one thing amongst many) to ask of other
designers it would be "Please don't create tab orders that are
unintuitive!". Users (in the West, anyway) expect tab ordering to follow
a left-to-right top-to-bottom rule and, as soon as you mess with that,
you create confusion.
By the 'Alt+# system', I assume you mean accesskeys. It's a way of
defining keyboard shortcuts which, in theory, allow users to jump to,
for example, the Search item on the menu by selecting ALT+s. Depending
on the browser being used, the user may then have to press ENTER to
activate the link. The designer can define which keys, in conjunction
with ALT (or CTRL on a Mac) relate to which links by means of the
accesskey attribute.
However, there are problems associated with defining accesskeys on a
site as they can over-ride pre-existing keyboard shortcuts in the user's
software.
http://www.wats.ca/show.php?contentid=43
has a fairly comprehensive list whilst
http://www.wats.ca/show.php?contentid=32
also has makes some interesting points.
Since the release of Firefox 2.0, there are also problems with using
numeric accesskeys on sites.
http://juicystudio.com/article/firefox2-accesskeys.php
My own experience and research suggests that most of the users that
designers *assume* will want to use accesskeys don't bother with them.
They vary too much from site to site to be really useful. Providing the
tab order is intuitive, users prefer to simply tab around pages or use
options within their own software (which they know far better than a
random site) to jump to specific points on a page or site rather than
research a whole list of new keyboard shortcuts on every site they visit.
Gez Lemon and Rich Pedley developed a php AccessKeys class that allows
users to define their own access keys . In theory, users could define
the same subset of keys on every site that uses this approach:
http://juicystudio.com/article/user-defined-accesskeys.php
Gez has also since developed an .ASP version:
http://juicystudio.com/article/user-defined-access-keys-aspversion.php
However, I don't think either version has been around long enough, or is
implemented widely enough, to indicate how many keyboard navigators
actually use make use of the facility when it's offered. I know I've
never bothered. :-)
Mel
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