在一个窗口中央加载一个任意位图，位图面积为窗口面积的四分之一，当即鼠标左键或键盘上的向上箭头时位图向上移动，当移动到上边界时，窗口显示“不能再向上移动了”字样，当点击鼠标右键或键盘上的向下箭头时，位图向下移动，当到达窗口的下边界时，屏幕显示“不能再向下移动了”字样。-window in a central loading an arbitrary Bitmap bitmap area of the quarter window area. immediately keyboard or mouse button on the upward arrow at the bitmap upward mobility, on the border of Mobile, window displays "no longer moving up the" words, when the right-click of a mouse or keyboard on the downward arrow, Bitmap moving down when they reach the border under the window, the screen shows "should no longer be moving down the" indication.