[orca-list] What is QT and why would we use it?

[Glenn <glennervin cableone net>]

Hi,
I read a reference to QT when I enquired about vBox, now QT is being 
mentioned again.

Can someone tell me what it is, and why it is needed?

I looked it up on the web, but did not find any real answers to my 
questions.

Thanks.
Glenn