You may earn extra credit by creating an applet that extends the checkerboard that you wrote for assignment 6. This applet will allow a user to put checkers (filled circles) on the squares. When the user clicks on a square, your applet should place a checker on that square. The checkers should be in a color other than those used for the squares.

A straightforward solution draws a circle with center at the location where the mouse was clicked. A more complicated one puts the center at the center of the square. This would require calculating the upper corner of the square from the x and y coordinates of the mouse click.

You probably should make the circles smaller than the squares, but not a lot smaller. For example, if the squares have side 30, the circles might have diameter 20.

This assignment will be worth 10 points and will be strictly for extra credit.