Adding a tooltip to a notebook tab

[Matt Bragano <maestro485 comcast net>]

I've got a notebook tab with a label widget for text.  Since the text 
length can sometime become overly long, I decided to truncate the text 
to make the tab a reasonable size and use a tooltip to display the full 
text.  This behavior is essentially the same thing Firefox does when you 
have a bunch of open tabs and move your mouse over one.

The problem is that the tooltip never appears.  I've tried attaching it 
to the label, the text, the return value of get_tab_label(), but nothing 
seems to work.  Also, I've used tooltips in other situations with no 
problems, so I don't think its a syntax error.

Is there a particular way to attach to a notebook tab, or might this be 
a bug?  Or maybe normal behavior for some reason I don't know about?

Thanks,
Matt Bragano