| 
 | virtual | 
Called by the framework to display the header control sort arrow.
Override OnDrawHeaderCtrlSortArrow in a derived class to customize the header control appearance.
| pCtrl | Points to a header control whose sort arrow is being drawn. | 
| pDC | A pointer to a device context. | 
| rect | The bounding rectangle of the sort arrow. | 
| bIsUp | If TRUE, this is the up arrow. If FALSE, this is the down arrow. |