This is the initial setting of the project. This is a simulated spring. When you move your cursor onto the gray part of the rectangle, it will turn bright and you can move it up an down.
After you press the spring with your mouse, then you can release your mouse. The spring will bounce up and down while colorful rectangles will fly out of the spring.
The rectangles will fall on to the floor due to gravity. And disappear after a while.
