Can't add resizable widget dynamically?

Can't add resizable widget dynamically?

CAVEAT: It's entirely likely this is my own stupidty and not a bug.  

Check out  this JSFiddle.  It creates a resizeable box, then adds another dynamically, and tries to initialize that, but only the first box is resizeable.

1) What is the correct way to do this?
2) (If I'm doing it semi-correctly), what is wrong here?