They use a trackball to move the cursor and scroll the screen, but it is more like cursor-key functionality rather than a mouse pointer.

它们使用轨迹球移动指针和滚动屏幕，但是这更像是指针-键功能而不是鼠标指针。

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Onscreen thumbwheels look rather like the scroll wheel on a mouse, and behave in much the same way.

屏幕上的拇指轮看上去就像鼠标上的滚动轮，行为也非常相似，并普遍用在某些三维程序中。

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