      *  may be recycled and its properties reset.  
      * 
      *  <p>If the requested header renderer is not visible then, 
-     *  each time this method is called, a new header renderer is created.  The
-     *  new item renderer is not visible</p>
+     *  each time this method is called, a new header renderer is created.  
+     *  The new item renderer is not visible</p>
      * 
      *  <p>The width of the returned renderer is the same as for item renderers
      *  returned by DataGrid/getItemRendererAt().</p>
      *  
-     *  @param columnIndex The 0-based column index of the header renderer's column
+     *  @param columnIndex The 0-based column index of the header renderer's column.
+     * 
      *  @return The item renderer or null if the column index is invalid.
      * 
      *  @langversion 3.0

     *  Specifies the column index of the header renderer currently
     *  being hovered over by the user.
     *  
     *  <p>Setting hoverColumnIndex to -1 (the default) means that the column index
     *  is undefined and the header renderer will have its hovered property set to false.</p>
     * 
     *  @default -1
     * 

[Event(name="gridMouseDrag", type="spark.events.GridEvent")]

/**
 *  Dispatched after a <code>gridMouseDown</code> event 
 *  when the mouse button is released, even
 *  if the mouse is no longer within the GridColumnHeaderGroup.
 *
 *  @eventType spark.events.GridEvent.GRID_MOUSE_UP
