ButtonBase The ButtonBase class is the base class for the all Spark button components.
 DisplayLayer A DisplayLayer class maintains an ordered list of DisplayObjects sorted on depth.
 DropDownController The DropDownController class handles the mouse, keyboard, and focus interactions for an anchor button and its associated drop down.
 DropDownListBase The DropDownListBase control contains a drop-down list from which the user can select a single value.
 GroupBase The GroupBase class defines the base class for components that display visual elements.
 InteractionState Values for the state property of the InteractionStateDetector class.
 InteractionStateDetector A helper class for components to use to help them determine if they should be in the up, over, or down states.
 ItemRenderer The ItemRenderer class is the base class for Spark item renderers.
 ListBase The ListBase class is the base class for all components that support selection.
 OverlayDepth The OverlayDepth class defines the default depth values for various overlay elements used by Flex.
 Range The Range class holds a value and an allowed range for that value, defined by minimum and maximum properties.
 ScrollBarBase The ScrollBarBase class helps to position the portion of data that is displayed when there is too much data to fit in a display area.
 Skin The Skin class defines the base class for all skins used by skinnable components.
 SkinnableComponent The SkinnableComponent class defines the base class for skinnable components.
 SkinnableContainerBase Base class for skinnable container components.
 SkinnableTextBase The base class for skinnable components, such as the Spark TextInput and TextArea, that include an instance of IEditableText in their skin to provide text display, scrolling, selection, and editing.
 StyleableTextField AIR-only The StyleableTextField class is a text primitive for use in ActionScript skins and item renderers.
 TextBase The base class for Spark text controls such as Label and RichText which display text using CSS styles for the default format.
 TextInputOperation AIR-only The TextInputOperation class represents a text input operation.
 ToggleButtonBase The ToggleButtonBase component is the base class for the Spark button components that support the selected property.
 TrackBase The TrackBase class is a base class for components with a track and one or more thumb buttons, such as Slider and ScrollBar.