import mx.styles.StyleManager;
[Embed("a.gif")]
public var os:Class;
[Embed("b.gif")]
public var ds:Class;
[Embed("a.gif")]
public var us:Class;
private function init():void {
StyleManager.getStyleDeclaration("Button").setStyle("upSkin", us);
StyleManager.getStyleDeclaration("Button").setStyle("overSkin", os);
StyleManager.getStyleDeclaration("Button").setStyle("downSkin", ds);
}