The EventDispatcher class is the base class for all classes that can dispatch events. The EventDispatcher class allows any object on the display list to be an event target and as such, to use the methods of the IEventDispatcher interface.

The UIComponent class is the base class for all visual components, both interactive and noninteractive.

The BorderContainer class provides a set of CSS styles that control the appearance of the border and background fill of the container.

The Form container provides control over the layout of a form, mark form fields as required or optional, handle error messages, and bind form data to the Flex data model to perform data checking and validation.

The VGroup container is a Group container that uses the VerticalLayout class.

The HGroup container is a Group container that uses the HorizontalLayout class.

The Panel class is a container that includes a title bar, a caption, a border, and a content area for its children.

The SkinnableContainer class is the base class for skinnable containers that provide visual content.

The TabBar displays a set of identical tabs.

The TitleWindow extends Panel to include a close button and move area.