Such discontiguous , incremental Undo so hard to explain in words is so natural and easy to use because everything is visible : Users can clearly see what will be backspaced away .
这种不连续的渐增撤销很自然,而且容易使用。这一点不好用语言解释,因为所有事物都是可见的,用户能清楚地看到什么被退格键删除了。