+1  A: 

I don't think you can do what you want. It seems like a hack anyway -- child DOM element attributes aren't meant to "override" parent attributes. You should probably wrap the specific text with the correct title, such as this:

http://jsbin.com/ezipe

desau
However, the "title" attribute in particular really can't work any other way. It's not invalid by any definition I can think of for a container to have a different title than a contained element, and the browser is only ever going to show me one title, that being the one "closest" to the element over which the mouse is paused.
Pointy
+1  A: 

Why not assign the title to the question mark element (#qmark) instead of the containing div? So instead of:

<div title="this is the overlapping title">  
    <div id="qmark">?</div>
    <div id="hiddenContainer"></div>
</div>  

it would be

<div>
    <div id="qmark" title="this title no longer overlaps">?</div> 
    <div id="hiddenContainer"></div>
</div>
eug
That's a fine idea, and in fact I started doing that after reading @desau's answer. Then I realized that my "help" bubbles may actually nested inside *another* layer of "title"-bearing markup. One might argue that I'm simply using too many of those and that I should get out of the habit, especially given the rise of "touch" interfaces where there's really no "hover" anyway.
Pointy
A: 

I ended up augmenting my existing code that opens/closes the "help" bubble so that it runs up the chain of parent elements and stashes the "title" code with the jQuery "data" facility. When the bubble closes, the titles are restored.

Pointy