Dashed guides when I edit components in Flash CS 5.5

How can I use those very useful guides that indicate which parts of component must be resized 开发者_Go百科and which not?

What is a proper name for them? How I can create them for a new component that I create from scratch?

Please see picture to understand what I am talking about.

Those are class slice9 guides. You can enable them for a new symbol by checking the "Enable guides for 9-slice scaling" checkbox in the new symbol window.

To use them, you drag them about just like normal guides. When your symbol is resized, only the area between two guides will be stretched, meaning that corners and border lines etc can keep their shape and size. Areas outside of the guides will be moved to fit the new shape without distorting.

This should illustrate more clearly: