http://www.soave.cn/post/2009/11/02/flex3and4_differences.aspx
http://www.adobe.com/cn/devnet/flex/articles/flex3and4_differences_04.html
【新增组件和容器】
Flex 4 beta 引入了许多使用新架构的新组件类，它们应当可以令外观和其他自定义操作更简单。下表列出了 Flex 3 Halo 组件及其 Flex 4 beta Spark 对应组件：
Flex 3 Halo 组件 | Flex 4 beta Spark 组件 |
mx.controls.Button | spark.components.Button |
mx.controls.ButtonBar | spark.components.ButtonBar |
mx.controls.CheckBox | spark.components.CheckBox |
mx.controls.ComboBox | spark.components.DropDownList（不可编辑） |
mx.controls.HorizontalList | spark.components.List（带一个 HorizontalLayout） |
mx.controls.HRule | spark.primitives.Line |
mx.controls.HScrollBar | spark.components.HScrollBar |
mx.controls.HSlider | spark.components.HSlider |
mx.controls.Image | spark.primitives.BitmapImage |
mx.controls.LinkBar | spark.components.ButtonBar（带一个自定义外观） |
mx.controls.LinkButton | spark.components.Button（带一个自定义外观） |
mx.controls.List | spark.components.List |
mx.controls.NumericStepper | spark.components.NumericStepper |
mx.controls.RadioButton | spark.components.RadioButton |
mx.controls.RadioButtonGroup | spark.components.RadioButtonGroup |
mx.controls.TextArea | spark.components.TextArea |
mx.controls.TextInput | spark.components.TextInput |
mx.controls.TileList | spark.components.List（带一个 TileLayout） |
mx.controls.ToggleButtonBar | spark.components.ButtonBar |
mx.controls.VideoDisplay | spark.components.VideoPlayer |
mx.controls.VRule | spark.primitives.Line |
mx.controls.VScrollBar | spark.components.VScrollBar |
mx.controls.VSlider | spark.components.VSlider |
mx.core.Application | spark.components.Application |
mx.core.Window | spark.components.Window |
mx.core.WindowedApplication | spark.components.WindowedApplication |
mx.containers.Canvas | spark.components.Group |
mx.containers.HBox | spark.components.HGroup |
mx.containers.Panel | spark.components.Panel |
mx.containers.Tile | spark.components.Group（带一个 TileLayout） |
mx.containers.VBox | spark.components.VGroup |
Adobe 鼓励您与 Spark 组件一起使用 Halo 组件和容器。由于 Adobe 在同一基类 (UIComponent) 上构建组件，Spark 与 Halo 之间应当可以实现全面的可互操作性。下表列出了目前没有 Spark 直接等效类的组件和容器。
Flex 3 类，没有直接的 Flex 4 beta 对应类 |
mx.controls.Alert |
mx.controls.ColorPicker |
mx.controls.DataGrid |
mx.controls.DateChooser |
mx.controls.DateField |
mx.controls.Menu |
mx.controls.MenuBar |
mx.controls.PopUpButton |
mx.controls.PopUpMenuButton |
mx.controls.ProgressBar |
mx.controls.RichTextEditor |
mx.controls.TabBar |
mx.controls.Tree |
mx.containers.Accordion |
mx.containers.ApplicationControlBar |
mx.containers.ControlBar |
mx.containers.DividedBox |
mx.containers.Form |
mx.containers.Grid |
mx.containers.TabNavigator |
mx.containers.TitleWindow |
mx.containers.ViewStack |
