             addEventListener(GridEvent.GRID_ROLL_OUT, header_rollOutHandler);
             
             addEventListener(GridEvent.SEPARATOR_MOUSE_DOWN, sep_mouseDownHandler);
+            addEventListener(GridEvent.SEPARATOR_MOUSE_UP, sep_mouseUpHandler);
             addEventListener(GridEvent.SEPARATOR_ROLL_OVER, sep_rollOverHandler);
             addEventListener(GridEvent.SEPARATOR_ROLL_OUT, sep_rollOutHandler);
         }

            {
                case MouseEvent.MOUSE_MOVE: 
                    if (dragSeparator)
                        gridEventType = GridEvent.SEPARATOR_MOUSE_DRAG;    
                    else
                        gridEventType = GridEvent.GRID_MOUSE_DRAG;
                    break;

         *  always a MOUSE_UP.  By default this method dispatches GRID_MOUSE_DOWN, 
         *  GRID_MOUSE_DRAG, or a GRID_MOUSE_UP event in response to the the corresponding
         *  mouse event on a column header or SEPARATOR_MOUSE_DOWN, SEPARATOR_MOUSE_DRAG, 
         *  or a SEPARATOR_MOUSE_UP event in response to the the corresponding
         *  mouse event on a column header separator.
         * 
         * .The GridEvent's columnIndex, column, item, and itemRenderer 
