About Spark containers

Spark includes the following containers:

Group and DataGroup
SkinnableContainer, SkinnableDataContainer, Panel, TitleWindow, NavigatorContent, BorderContainer, and Application

Note: The Panel and NavigatorContent classes are subclasses of the SkinnableContainer class. The information below for SkinnableContainer applies also to the Panel and NavigatorContent classes.

For more information on the Application container, see Application containers.

All Spark containers support interchangeable layouts. That means you can set the layout of a container to any of the supported layout types, such as basic, horizontal, vertical, or tiled layout. You can also define a custom layout.

To improve performance and minimize application size, some Spark containers do not support skinning. Use the Group and DataGroup containers to manage child layout. Use SkinnableContainer and SkinnableDataContainer to manage child layout and to support custom skins.

The Group and SkinnableContainer classes can take any visual components as children. Visual components implement the IVisualElement interface, and include subclasses of the UIComponent class and the GraphicElement class.

The UIComponent class is the base class of all Flex components. Therefore, you can use any Flex component as a child of the Group and SkinnableContainer class.

The GraphicElement class is the base class for the Flex drawing classes, such as the Ellipse, Line, and Rect classes. Therefore, you can use subclass of the GraphicElement class as a child of the Group and SkinnableContainer class.

The DataGroup and SkinnableDataContainer classes take as children visual components that implement the IVisualElement interface and are subclasses of DisplayObject. This includes subclasses of the UIComponent class.

However, the DataGroup and SkinnableDataContainer containers are optimized to hold data items. Data items can be simple data items such as String and Number objects, and more complicated data items such as Object and XMLNode objects. Therefore, while these containers can hold visual children, use Group and SkinnableContainer for children that are visual components.

The following table lists the main characteristics of the Spark containers:

	Children	Skinnable	Scrollable	Creation policy	Primary use
Group	IVisualElement	No	As a child of Scroller	All	Lay out visual children.
DataGroup	Data Item IVisualElement and DisplayObject	No	As a child of Scroller	All	Render and lay out data items.
SkinnableContainer	IVisualElement	Yes	By skinning	Selectable	Lay out visual children in a skinnable container.
SkinnableDataContainer	Data item IVisualElement and DisplayObject	Yes	By skinning	Selectable	Render and lay out data items in a skinnable container.
BorderContainer	IVisualElement	No	No	Selectable	Lay out visual children in a nonskinnable container that includes a border.
NavigatorContent	IVisualElement	Yes	By skinning	Inherited from parent container	Subclass of SkinnableContainer that can be used as the child of an MX navigator container.
Panel	IVisualElement	Yes	By skinning	Selectable	Subclass of SkinnableContainer that adds a title bar and other visual elements to the container.
TitleWindow	IVisualElement	Yes	By skinning	Selectable	Subclass of Panel that is optimized for use as a pop-up window.

For information on skinning, see Spark Skinning. For information on creation policy, see About the creation policy.