sometime ago I read this article that shows a way to implement mouse resizable components in Swing.
The author uses a null LayoutManager in order to allow absolute c
I guess it would depend on the specifics of how you wanted it to behave.
The main reason the null layout manager is discouraged is because of the fact that interfaces built using that can only be used in the size they were designed - You can't resize the UI. If this is fine for you, use it.
Another option I know of is the AbsoluteLayout that Netbeans is distributed with. You can get more info here: http://www.java-tips.org/other-api-tips/netbeans/can-i-distribute-absolutelayout-with-my-applica.html. I think this might be exactly what you are looking for, but as you can see from that link, they recommend rather using a Null layout... I don't think it makes much of a difference either way.
If you need to be able to allow users to define how the components will resize as well, you'll end up building something like the Netbeans Matisse form designer, which is probably overkill and does not strike me as much fun :)