XSpringies is a mass and spring simulation system.  It's intended use is more
like that of a game, than some design package.

It's written using Xlib only.  No Motif or any other widgets sets are used.

The animation in XSpringies is done using an off-screen Pixmap.  The next
frame is drawn on this pixmap, then is blitted onto the screen.  Since the
frame rate is about 30 frames per second, slower machines (or machines which
have poorly written bit-blitting code) will be deathly slow and blinky.