The mx.core package contains the base classes and interfaces, such as UIComponent, used by Flex.

	Interface	Description
	IAssetLayoutFeatures	The IAssetLayoutFeatures interface defines the minimum properties and methods required for an Object to support advanced transforms in embedded assets.
	IBorder	The IBorder interface defines the interface that all classes used for border skins should implement.
	IButton	The IButton interface is a marker interface that indicates that a component acts as a button.
	IChildList	The IChildList interface defines the properties and methods for accessing and manipulating child lists, which are subsets of a DisplayObjectContainer's children.
	IConstraintClient	The IConstraintClient interface defines the interface for components that support layout constraints.
	IContainer	IContainer is a interface that indicates a component extends or mimics mx.core.Container
	IDataRenderer	The IDataRenderer interface defines the interface for components that have a data property.
	IDeferredContentOwner	The IDeferredContentOwner interface defines the properties and methods for deferred instantiation.
	IDeferredInstance	The IDeferredInstance interface defines the Flex deferred instance factory interface.
	IDeferredInstantiationUIComponent	The IDeferredInstantiationUIComponent interface defines the interface for a component or object that defers instantiation.
	IFactory	The IFactory interface defines the interface that factory classes such as ClassFactory must implement.
	IFlexAsset	IFlexAsset is a marker interface with the following meaning: if a class declares that it implements IFlexAsset, then that class represents an asset -- such as a bitmap, a font, or a sound -- that has been embedded in a Flex application.
	IFlexDisplayObject	The IFlexDisplayObject interface defines the interface for skin elements.
	IFlexModule	The IFlexModule interface is used as an optional contract with IFlexModuleFactory.
	IFlexModuleFactory	The IFlexModuleFactory interface represents the contract expected for bootstrapping Flex applications and dynamically loaded modules.
	IFontContextComponent	Allows a component to support a font context property.
	IIMESupport	The IIMESupport interface defines the interface for any component that supports IME (input method editor).
	IInvalidating	The IInvalidating interface defines the interface for components that use invalidation to do delayed -- rather than immediate -- property commitment, measurement, drawing, and layout.
	ILayoutDirectionElement	The ILayoutDirectionElement interface defines the minimum properties and methods required for an Object to support the layoutDirection property.
	ILayoutElement	The ILayoutElement interface is used primarily by the layout classes to query, size and position the elements of GroupBase containers.
	IMXMLObject	The IMXMLObject interface defines the APIs that a non-visual component must implement in order to work properly with the MXML compiler.
	INavigatorContent	The INavigatorContent interface defines the interface that a container must implement to be used as the child of a navigator container, such as the ViewStack, TabNavigator, and Accordion navigator containers.
	IProgrammaticSkin	The IProgrammaticSkin interface defines the interface that skin classes must implement if they use the name property skin interface.
	IPropertyChangeNotifier	The IPropertyChangeNotifier interface defines a marker interface.
	IRawChildrenContainer	The IRawChildrenContainer interface defines the APIs for containers that can return an IChildList that represents all their children.
	IRectangularBorder	The IRectangularBorder interface defines the interface that all classes used for rectangular border skins should implement.
	IRepeater	The IRepeater interface defines the public APIs of the Repeater object.
	IRepeaterClient	The IRepeaterClient interface defines the APIs for components that can have multiple instances created by a Repeater.
	ISelectableList	The ISelectableList interface indicates that the implementor is an IList element that supports a selectedIndex property.
	IStateClient	The IStateClient interface defines the interface that components must implement to support view states.
	IStateClient2	The IStateClient2 interface defines the interface that components must implement to support Flex 4 view state semantics.
	ISWFBridgeGroup	A sandbox bridge group is a group of bridges that represent applications that this application can communicate with.
	ISWFBridgeProvider	An implementor of ISWFBridgeProvider provides a bridge to an application in a different security sandbox or to an application that was compiled with a different version of the Flex compiler and is running in a separate ApplicationDomain.
	ISWFLoader	The ISWFLoader interface defines an API with special properties and method required when loading compatible applications and untrusted applications.
	ITextInput	Defines an interface for a single-line text field that is optionally editable.
	IToggleButton	The IToggleButton interface is a marker interface that indicates that a component acts as a toggleable button.
	IToolTip	The IToolTip interface defines the API that tooltip-like components must implement in order to work with the ToolTipManager.
	ITransientDeferredInstance	The ITransientDeferredInstance interface extends IDeferredInstance and adds the ability for the user to reset the deferred instance factory to its initial state (usually this implies releasing any known references to the component, such as the setting the owning document property that refers to the instance to null).
	IUIComponent	The IUIComponent interface defines the basic set of APIs that you must implement to create a child of a Flex container or list.
	IUID	The IUID interface defines the interface for objects that must have Unique Identifiers (UIDs) to uniquely identify the object.
	IUITextField	The IUITextField interface defines the basic set of APIs for UITextField instances.
	IVisualElement	The IVisualElement interface defines the minimum properties and methods required for a visual element to be laid out and displayed in a Spark container.
	IVisualElementContainer	The IVisualElementContainer interface defines the minimum properties and methods required for a container to manage Spark components for display.
	IWindow	The IWindow interface defines the API for components that serve as top-level containers in Flex-based AIR applications (containers that represent operating system windows).

	Class	Description
	Application	Flex defines a default, or Application, container that lets you start adding content to your application without explicitly defining another container.
	BitmapAsset	BitmapAsset is a subclass of the flash.display.Bitmap class which represents bitmap images that you embed in a Flex application.
	ButtonAsset	ButtonAsset is a subclass of the flash.display.SimpleButton class which represents button symbols that you embed in a Flex application from a SWF file produced by Flash.
	ByteArrayAsset	ByteArrayAsset is a subclass of the flash.utils.ByteArray class which represents an arbitrary sequence of byte data that you embed in a Flex application.
	ClassFactory	A ClassFactory instance is a "factory object" which Flex uses to generate instances of another class, each with identical properties.
	ComponentDescriptor	ComponentDescriptor is the base class for the UIComponentDescriptor class, which encapsulates the information that you specified in an MXML tag for an instance of a visual component.
	Container	The Container class is an abstract base class for components that controls the layout characteristics of child components.
	ContainerCreationPolicy	The ContainerCreationPolicy class defines the constant values for the creationPolicy property of the Container class.
	ContainerLayout	The ContainerLayout class defines the constant values for the layout property of container classes.
	ContextualClassFactory	A class factory that provides a system manager as a context of where the class should be created.
	DeferredInstanceFromClass	A deferred instance factory that creates and returns an instance of a specified class.
	DeferredInstanceFromFunction	A deferred instance factory that uses a generator function to create an instance of the required object.
	DesignLayer	The DesignLayer class represents a visibility group that can be associated with one or more IVisualElement instances at runtime.
	DragSource	The DragSource class contains the data being dragged.
	EdgeMetrics	The EdgeMetrics class specifies the thickness, in pixels, of the four edge regions around a visual component.
	EventPriority	The EventPriority class defines constant values for the priority argument of the addEventListener() method of EventDispatcher.
	FlexBitmap	FlexBitmap is a subclass of the Player's Bitmap class.
	FlexGlobals	A class that contains variables that are global to all applications within the same ApplicationDomain.
	FlexHTMLLoader	FlexHTMLLoader is a subclass of the Player's HTMLLoader class used by the Flex HTML control.
	FlexLoader	FlexLoader is a subclass of the Player's Loader class.
	FlexMovieClip	FlexMovieClip is a subclass of the Player's MovieClip class.
	FlexShape	FlexShape is a subclass of the Player's Shape class.
	FlexSimpleButton	FlexSimpleButton is a subclass of the Player's SimpleButton class.
	FlexSprite	FlexSprite is a subclass of the Player's Sprite class and the superclass of UIComponent.
	FlexTextField	FlexTextField is a subclass of the Player's TextField class and the superclass of UITextField.
	FlexVersion	This class controls the backward-compatibility of the framework.
	FontAsset	FontAsset is a subclass of the flash.text.Font class which represents fonts that you embed in a Flex application.
	FTETextField	FTETextField is a Sprite which displays text by using the new Flash Text Engine to implement the old TextField API.
	LayoutContainer	Flex defines a default, or Application, container that lets you start adding content to your module or Application without explicitly defining another container.
	LayoutDirection	The LayoutDirection class defines the constant values for the layoutDirection style of an IStyleClient and the layoutDirection property of an ILayoutDirectionElement.
	MovieClipAsset	MovieClipAsset is a subclass of the flash.display.MovieClip class which represents movieclip symbols that you embed in a Flex application from a SWF file produced by Flash.
	MovieClipLoaderAsset	MovieClipLoaderAsset is a subclass of the MovieClipAsset class which represents SWF files that you embed in a Flex application.
	MXMLObjectAdapter	The MXMLObjectAdapter class is a stub implementation of the IMXMLObject interface, so that you can implement the interface without defining all of the methods.
	Repeater	The Repeater class is the runtime object that corresponds to the <mx:Repeater> tag.
	ScrollControlBase	The ScrollControlBase class is the base class for controls with scroll bars.
	ScrollPolicy	Values for the horizontalScrollPolicy and verticalScrollPolicy properties of the Container and ScrollControlBase classes.
	SoundAsset	SoundAsset is a subclass of the flash.media.Sound class which represents sounds that you embed in a Flex application.
	SpriteAsset	SpriteAsset is a subclass of the flash.display.Sprite class which represents vector graphic images that you embed in an application.
	SWFBridgeGroup	A SWFBridgeGroup represents all of the sandbox bridges that an application needs to communicate with its parent and children.
	TextFieldAsset	TextFieldAsset is a subclass of the flash.text.TextField class which represents TextField symbols that you embed in a Flex application from a SWF file produced by Flash.
	UIComponent	The UIComponent class is the base class for all visual components, both interactive and noninteractive.
	UIComponentCachePolicy	The ContainerCreationPolicy class defines the constant values for the cachePolicy property of the UIComponent class.
	UIComponentDescriptor	A UIComponentDescriptor instance encapsulates the information that you specified in an MXML tag for an instance of a visual component.
	UIFTETextField	The UIFTETextField class is an alternative to the UITextField class for displaying text in MX components.
	UITextField	The UITextField class defines the component used by many Flex components to display text.
	UITextFormat	The UITextFormat class represents character formatting information for the UITextField class.
	Window	The Window is a top-level container for additional windows in an AIR desktop application.
	WindowedApplication	The WindowedApplication defines the application container that you use to create Flex applications for AIR applications.