Chapter 20, Problem 20.5PE

(Combine colliding bouncing balls) The example in Section 20.8 displays multiple bouncing balls. Extend the example to detect collisions. Once two balls collide, remove the later ball that was added to the pane and add its radius to the other ball, as shown in Figure 20.17b. Use the Suspend button to suspend the animation, and the Resume button to resume the animation. Add a mouse-pressed handler that removes a ball when the mouse is pressed on the ball.