Swing API for Workflow drawing application

Hi,

I'm looking to evaluate some swing based API's which can be used to
develop an application for drawing/developing workflows. Can any one
suggest some good ones? What is expected out of the application to be
developed is capabilities similar to the GUI builder of
NetBeans(draggable elements, grid based alignment, drag elements from
a list to a work area etc) plus drawing connector lines to join
various elements in the workflow chart.

Thanks in advance

Chanchal
.