The Color Selection Tool has only one function, but it is a useful one. The Color Selection Tool can be used to "pick up" colors that you've already used in an icon. You want to pick a specific shade, but there are several that are so similar that it's difficult for your eye to distinguish between them.

Just click on the Color Selection Tool, and click on the exact portion of the icon that contains the color that you want. The active color for your tools will automatically change to the color that you picked with the Color Selection Tool.

In addition, the Color Selection Tool will automatically switch over to the previously selected tool, enabling you to rapidly resuming work on the icon with the color you just selected.

You can use the Color Selection Tool to select color for the background color by using the right button on your mouse.