# How it works

At the heart of StackView are three layers of embedded [DesktopContainers](https://documentation.xojo.com/api/user_interface/desktop/desktopcontainer.html).

The top layer is a DesktopContainer of type [ViewController](/add-ons/stackview/version-3/details/viewcontroller.md) `3`. You design your interface on a ViewController.

Each ViewController is embedded in another DesktopContainer of type [StackController](/add-ons/stackview/version-3/details/stackcontroller.md) `2`. The StackController is responsible for showing and hiding the embedded ViewControllers and provide a heading as well.

Finally StackControllers are embedded in a DesktopContainer of type [ScrollController](/add-ons/stackview/version-3/details/scrollcontroller.md) `1` . These deal with scrolling if the shown embedded controls take up more space when is available.

![Structure](/files/-LMNHsZHBj_YMmwve3Bl)


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