[whatwg] Scoped tabindex proposal

[Martin Atkins]

Simon Pieters wrote:
> 
> So here's an idea. A new value for the tabindex attribute, "scoped". 
> Here's an example:
> 
>   <p>The following links should be focused in the order which the link 
> text indicates:
>   <p><a href="#">first</a>
>   <table tabindex="scoped">
>    <tr>
>     <td><a href="#" tabindex="1">second</a>
>     <td><a href="#" tabindex="3">forth</a>
>    <tr>
>     <td><a href="#" tabindex="2">third</a>
>     <td><a href="#" tabindex="4">fifth</a>
>   </table>
>   <p><a href="#">last</a>
> 
> The table itself is not in the tab order and is not focusable.
> 

The table might not be focusable, but it needs to be in the tab order in 
some sense in order to resolve that local tabindex="1" into a global 
tabindex.

For example:

<a id="outside1" href="..." tabindex="1">...</a>

<div tabindex="scoped" id="container1">
<a id="inside1" href="..." tabindex="1">...</a>
</div>

<div tabindex="scoped" id="container2">
<a id="inside2" href="..." tabindex="1">...</a>
</div>

<a id="outside2" href="..." tabindex="2">...</a>

What is the global tab order now?

I could see arguments for either:
#outside1
#inside1
#inside2
#outside2
(DOM order)

or...
#outside1
#outside2
#inside1
#inside2
(all of the explicit tabindexes first in index order, followed by 
everything else in DOM order)

Now what if I want the elements of #container2 to be before those of 
#container1 in the tab order? Can I also give these DIVs a tabindex?