      */
     public var incrementButton:Button;
     
-    [SkinPart(required="true")]
+    [SkinPart(required="false")]
     
     /**
      *  A skin part that defines the  button that, 

    //
    //--------------------------------------------------------------------------
    
    [SkinPart(required="true")]
    
    /**
     *  A skin part that defines the  button that, 

 *  @productversion Flex 4
 */
[Event(name="change", type="flash.events.Event")]

/**
 *  The alpha of the focus ring for this component.
 * 
 *  @langversion 3.0
 *  @playerversion Flash 10
 *  @playerversion AIR 1.5
 *  @productversion Flex 4
 */
[Style(name="focusAlpha", type="Number", inherit="no", theme="spark")]

/**
 *  @copy spark.components.supportClasses.GroupBase#style:focusColor
