Click in the applet window and use the following key commands:
1 - Toggle Gravity (default: off)
2 - Toggle World Spring (default: off)
3 - Toggle Spring Between Boxes (default: off)
4 - Toggle Damping (default: off)
Original application by Chris Hecker
Port to Java by me...(approx. 1 hour/1.25 CDs)

If key presses aren't working, click mouse inside applet and try again