 
 import mx.core.ClassFactory;
 import mx.core.IFactory;
+import mx.core.Singleton;
 import mx.core.mx_internal;
-import mx.core.Singleton;
-
+
+import spark.components.DataGrid;
 import spark.components.Grid;
 
 use namespace mx_internal;

        
        _headerRenderer = value;
        
        // TBD: invalidate the CHB
        
        dispatchChangeEvent("headerRendererChanged");
    }

    [Bindable("headerRendererChanged")]
    
    /**
     *  A factory for the IGridItemRenderer used as the header for this column.  If null,
     *  the value of the DataGrid headerRenderer property is returned. 
     * 
     *  @default null
     *
