Use the mouse to drag a piece from one board grid location to another. Try clicking on the mouse and releasing it. How does the program decide which playing piece the user wants to move? How does the program decide which board grid location the user wants the piece moved to?
Red Starts. Look at status window at the bottom of the browser. You may need to enable the status window by selecting menu View ->Status Bar.
A legal move has to be horizontal, diagonal, or vertical. Try moving a piece in a direction that is not legal. What types of illegal moves can you still make? What additional checks does the program need to make to identify those moves as illegal?