This is an archived snapshot of W3C's public bugzilla bug tracker, decommissioned in April 2019. Please see the home page for more details.
Please see my change proposal for the meta generator issue: http://www.w3.org/html/wg/wiki/TitleKeyContentMark During the writing of that proposal, it became evident that Firefox does not render a tooltip if the only content of a @title attribute is white-space. This seems to be the case for most/all of the characters of the White_Space and the Pattern_White_Space cathegory http://unicode.org/Public/UNIDATA/PropList.txt (However, it - somewhat illogically - fails to avoid the tooltip for the characters with 'ZERO WIDTH' as part of its name.) The Firefox behavior seems useful because it (a) avoid unintended tooltips (presumably this is why Firefox has this behavior) (b) it allows the title attribute to be used - without visually disturbing sighted users - as an explicit 'key content trigger' for images in lack of alt. (See my change prop for more data on this.) Thus, I propose to require roughly the same behavior from all browser. Cross browser, this - or _almost_ this behavior - is only seen for the MONGOLIAN VOWEL SEPARATOR character (U+180E). However, IE10 and Opera breaks the cross browser unity ...
EDITOR'S RESPONSE: This is an Editor's Response to your comment. If you are satisfied with this response, please change the state of this bug to CLOSED. If you have additional information and would like the Editor to reconsider, please reopen this bug. If you would like to escalate the issue to the full HTML Working Group, please add the TrackerRequest keyword to this bug, and suggest title and text for the Tracker Issue; or you may create a Tracker Issue yourself, if you are able to do so. For more details, see this document: http://dev.w3.org/html5/decision-policy/decision-policy.html Status: Rejected Change Description: No spec change. Rationale: The spec doesn't require title="" to ever produce a tooltip; the rules that some UAs use to choose whether or not to display title="" as a tooltip in their UI thus seem out-of-scope.