/**
  * End game method. Sets all spaces to not be clickable, resets the toolbar at the top of the
  * window, clears the stack, and resets the controller so its ready for a new game.
  */
 private void gameOver() {
   gui.resetBackgrounds();
   gui.resetToolbar();
   moveStack = new Stack<Move>();
   currentColor = WHITE;
   currentPiece = null;
 }