Yahoo Beta Column Adjuster

If you've played around with Yahoo's new Beat email interface you'll notice that they now have adjustable columns to reveal the from, subject, date, size information. This is also found in Outlook and all windows OS. Placing your cursor between two columns allows you to move a column left or right to reveal content of each row.

Does anyone know how this is done? I have not seen it anywhere else on the internet, but in Yahoo's beta email.

I've attached a screenshot taken from my yahoo.

Thanks in advance!!!!

Hmm.. based on drag and drop, kinda, you could have something like it. But it is quite complex, really.
Possible in Javascript, though.
I can't code it, personally (as JS isn't my area), but someone else may be able to help you.