public void checkMouse()
    {
        // send cursor value to mouse variable
        MouseInfo mouse = Greenfoot.getMouseInfo();
        int changeX;
        int mouseX;
        int mouseY;
        // check don't exceed left and right border of background
        // don't move paddle before player shoots
        if (Greenfoot.mouseClicked(null)) 
        {
            // once clicked, remove menu
            removeObject(menu); 
            // fixes bug. Instead of boolean, increase int by 1 to meet the if statement of ball launch.           
            clickMenu++;                                   
        }

        // if ball has launched, move paddle according to user input
        if (start)
        {
            if (Greenfoot.mouseMoved(null) && mouse.getX() > (paddle.getImage().getWidth())/3 && mouse.getX() <  (getWidth()+5) - paddle.getImage().getWidth()/2) 
            {     
                // calculate difference for actual magnitude moved
                changeX = mouse.getX()-paddle.getX(); 
                // move paddle accordingly
                movePaddle(changeX);
            }
        }

        // boolean does NOT work. Since the click from the menu will meet this statement. As a result, ball launches immediatly after menu screen.
        if (clickMenu>2)
        {
            if(paddle.haveBall() && Greenfoot.mouseClicked(null)) 
            {
                // release ball 
                start = true;  
                mouseX = mouse.getX();
                mouseY= mouse.getY();  
                // launches ball according to angle of launch
                launchBall(mouseX,mouseY);   
                // removes pointer
                removeObject(aim);
            }
        }

    }