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Re: How aria-multiselectable applies to TreeViews

From: Hans Hillen <hans.hillen@gmail.com>
Date: Wed, 8 Dec 2010 14:30:39 +0100
Cc: James Craig <jcraig@apple.com>, "wai-xtech@w3.org" <wai-xtech@w3.org>, Victor Tsaran <vtsaran@yahoo-inc.com>, Richard Schwerdtfeger <schwer@us.ibm.com>, Satyam Utsa <satyamutsa@yahoo.com.ar>
Message-Id: <B049F07B-8344-4BEB-8909-BDC95D4FE445@gmail.com>
To: Todd Kloots <kloots@yahoo-inc.com>
Hi todd,

I have a very basic example tree that uses aria-multiselectable="true" here: http://www.paciellogroup.com/blog/misc/samples/aria/tree/ . (The first treeview is multiselectable).

It doesn't indicate partially selected branches though. I think the best approach for indicating these would be to simply use aria-checked rather than aria-selected, and set aria-checked="mixed" on branch nodes where applicable. I'm not really sure if this fit's in the spec though, for example whether that would make sense in combination with  aria-multiselectable="true" (since you wouldn't really be using selection anymore). Also, I vaguely remember the ARIA specs once mentioning that the "mixed" value was only allowed on checkboxes (and therefore not on treeitem roles), but I can't find that anywhere in the latest version so maybe it's OK now.

Using aria-checked="mixed"  might be the easiest solution since it doesn't require a change to the spec, and many multiselectable treeviews would already use checboxes to indicate their selected state anyway. Of course if anybody can tell me why this is a bad idea, I'm all ears.


Hans Hillen

On Dec 3, 2010, at 1:03 AM, Todd Kloots wrote:

> James - 
> I think you misread my email.  I was asking for guidance rather than arguing a position.  I am confused how "aria-multiselectable" is designed to work with the "tree" role - not the "menu" role.  Specifically, how do we indicate the selected state of a parent node in a tree control if only some of the node's children are selected?  For example, consider the following markup:
> <ul role="tree" aria-multiselectable="true">
>  <li role="presentation">
>    <a role="treeitem" aria-expanded="true" href="#group-1">Fruits</a> <!-- parent node -->
>    <ul id="group-1" role="group">
>      <li role="treeitem" aria-selected="true">Apple</li>
>      <li role="treeitem" aria-selected="false">Orange</li>
>      <li role="treeitem" aria-selected="true">Pear</li>      
>    </ul>
>  </li>
> </ul>
> In this instance would the parent "Fruits" treeitem have an "aria-selected" state value of "true" or "false"?  Or does this use case illustrate the need for a value of "mixed"?
> - Todd
> On Dec 2, 2010, at 3:16 PM, James Craig wrote:
>> I'm not opposed to opening an ARIA 2.0 issue for adding a "mixed" state for aria-selected, but you'll be able to sell the idea better if you come up with a real-world scenario where this might be useful. Many cases would/could be covered by nested menus with groups of menuitemradio elements. 
>> On Nov 26, 2010, at 4:18 PM, Todd Kloots wrote:
>>> I am curious how it is imagined that the "aria-multiselectable" and "aria-selected" properties apply to a TreeView control?  The ARIA spec indicates that the "aria-multiselectable" property can be used with the the "tree" role, and the "aria-selected" state with "treeitem".  However, the "aria-selected" state only accepts a boolean.  How should developers indicate parent nodes in a partially selected stated - some tree items selected, some not.  And how is a screen reader supposed to announce the partially selected state of a parent node?
>>> I've yet to find any ARIA TreeView examples that make use of "aria-multiselectable", but considering the spec indicates that it applies to trees and the ARIA Authoring Practices specifies keyboard shortcuts for supporting multiple selection on trees, I figured some thought must have been given to this use case.
>>> Any insight would be greatly appreciated.
>>> Thanks,
>>> Todd
Received on Wednesday, 8 December 2010 14:27:30 UTC

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