 public class ButtonBase extends SkinnableComponent implements IFocusManagerComponent
 {
     include "../../core/Version.as";
+    
+    //--------------------------------------------------------------------------
+    //
+    //  Class mixins
+    //
+    //--------------------------------------------------------------------------
+
+    /**
+     *  @private
+     *  Placeholder for mixin by ButtonAccImpl.
+     */
+    mx_internal static var createAccessibilityImplementation:Function;
 
     //--------------------------------------------------------------------------
     //

[DefaultTriggerEvent("click")]

[DefaultProperty("label")]

/**
 *  The ButtonBase component is the base class for the all Spark button components.

    //  Overridden properties: UIComponent
    //
    //--------------------------------------------------------------------------
     /**
     *  @private
     */
    override protected function initializeAccessibility():void
    {
        if (ButtonBase.createAccessibilityImplementation != null)
            ButtonBase.createAccessibilityImplementation(this);
    }
    
    //----------------------------------
    //  baselinePosition
    //----------------------------------
