Hi, I think tabindex="" has a number of problems:
1) Lacking a feature to scope tabindexes into local contexts, which I proposed[1] a while back, makes the feature rather useless for its intended purpose (which, AIUI, was to provide a means for the author to suggest a different tab order than the natural one, because he was using, say, form controls in a table where the navigation should go down through the columns rather than row for row).
2) Using tabindex=0 or -1 to indicate whether an element can have focus is arguably bogus IMHO. Whether something is focusable depends on the UA or the device. I don't see any reason why apps would use <span tabindex=0 onclick onkeypress> instead of just using links, form controls, or contenteditable="" (depending on what you're doing). (If you'd do this because form controls are hard to style, then HTML isn't the place to address that problem.)
3) The "tab order" should be up to the user. In Opera you can navigate in any direction you want using e.g. Shift+arrows, allowing you to freely navigate in tables for instance. The author shouldn't have any say about the tab order other than the source order.
From what I've seen, most authors who use tabindex use it out of a cargo cultish habit thinking it would "aid accessibility" because some outdated accessibility guidelines told them so. The result mostly being reducing keyboard usability by distorting the tab order, because the elements with tabindex receive focus before anything else on the page. These authors don't realise how tabindex actually works, but they feel good about having added it because they comply with the accessibility guidelines, yet they don't know that it in fact screws up the tab order because they don't browse with the keyboard.
It was pointed out on IRC that there might be valid use-cases for #2, e.g. making a <canvas> focusable for games with keyboard controls. Then that's ok with me, I don't have strong opinions on this either way, I just think existing elements should be used where possible instead of reinventing links or checkboxes with <span tabindex> or similar.
However, for positive values of tabindex, I only see problems. The source order should be a powerful enough mechanism for authors to suggest a tab order of elements. I would love to see browsers treat all positive values for tabindex as equivalent to 0 (i.e., just make it focusable but don't change the tab order). I would also like to propose that positive values for tabindex be disallowed in HTML5 documents. I don't think it's a good idea to add a scoped tabindex feature (trying to address #1) as I proposed before.
[1] http://lists.whatwg.org/pipermail/whatwg-whatwg.org/2006-August/007228.html
Regards, -- Simon Pieters
