当用户选择一个对象后，从对象的中心有一条垂直线扩展到网格。

When a user selects an object, a vertical line extends from the center of the object to the grid.

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在精心定义的网格系统下进行设计，可以方便地扩展和修改，从而帮助开发者在各种候选方案中选择出具有最合适布局的方案。

A well-defined and communicated grid system results in designs that can be modified and extended, allowing developers to make appropriate layout decisions should alterations prove necessary.

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