lready exist. Multiples of clicks are not permitted.
        %
        % *Paramters*
        %
        % |x|: x coordinate
        %
        % |y|: y coordinate
        function addClickToStack(obj, x, y)
            if obj.indexOf(x, y) == -1
                obj.stack(end + 1, :) = [x, y];
            end
        end
        
        %% removeClickFromStack
        % Removes an (_x_, _y_) from the stack.
        %
        % *Paramters*
        %
        % |x|: x coordinate
        %
        % |y|: y coordi