ISSUE-406: Proposal for new aria-tooltip property. (Previously proposed as @aria-help)

From the discussion on this morning’s call regarding @aria-help or @aria-tooltip. Note: If you want to 


aria-tooltip (property)

Defines a string value that provides complementary tooltip or help text information for the current element. Also see aria-label.

The purpose of aria-tooltip is to provide additional information that complements the label text. For example, if the visible label of a tab is "General", the value of aria-help may be, "Displays general preferences for the application, such as home page, history, and download preferences." 

Authors SHOULD NOT provide a value for aria-tooltip that duplicates information already provided as all or part of the element's accessible name (label). Authors SHOULD NOT provide a value for @aria-tooltip if that information is already provided using the host language’s tooltip attribute, such as @title in HTML.


Tooltip/Help Computation 

1. If the element has a non-empty "aria-tooltip" attribute, user agents will expose the value of that attribute as the Tooltip/Help value in the accessibility API.
2. If the element has an explicitly empty "aria-tooltip" attribute, (aria-tooltip=""), user agents will expose no Tooltip/Help value in the accessibility API. 
3. If the element has no "aria-tooltip" attribute, but the "aria-describedby" attribute references a single element whose role is "tooltip", user agents must calculate the description using the text alternative algorithm and expose that string as the Tooltip/Help value in the accessibility API. 
4. Otherwise, if there is no ARIA-based tooltip, and the element includes the generic tooltip attribute (such as @title in HTML), and if the tooltip attribute has NOT been used in the name computation for the element, user agents MUST expose the value of the tooltip attribute (e.g. @title in HTML) as the Tooltip/Help value in the accessibility API.


Related Concepts

Help Tag (Apple Human Interface Guidelines)
http://developer.apple.com/mac/library/documentation/UserExperience/Conceptual/AppleHIGuidelines/XHIGUsingTechnologies/XHIGUsingTechnologies.html#//apple_ref/doc/uid/TP30000355-TPXREF9

AXHelp (Apple AX API)
http://developer.apple.com/mac/library/documentation/Accessibility/Reference/AccessibilityLowlevel/AXAttributeConstants_h/CompositePage.html#//apple_ref/c/macro/kAXHelpAttribute

Cynthia, please provide a link to the UIA tooltip pattern you mentioned. I’ll add it.