tooltip for layer name in map layers widget

Is there any way to configure a tooltip so that it will appear when a user hovers the mouse over a layer name in the map layers widget?

 

I thought perhaps if I defined the 'description' field on the map layer's 'Details' tab that it do what I wanted but it doesn't appear that the description appears anywhere in the HTML5 viewer.  Not sure what purpose it serves - the admin guide says it is 'to use as metadata' but doesn't explain how.

 

Anyways, if anyone has done this before or has an idea how it could be accomplished I'd like to hear from you.

 

Peter.