Change Look & Feel in open JFrame s & JDialog s

From: <- Chameleon -> (cham_gss_at_hotmail.NOSPAM.com)
Date: 09/29/04 

Date: Wed, 29 Sep 2004 23:05:41 +0300

I have 3 open JFrame s and from a JDialog which is "Options" of my program,
I change Look & Feel from "Windows" to "Metal".

How can I change Look & Feel of opened JFrame s without .dispose() and
recreate?

thanks