function _fnSortAttachListener ( settings, attachTo, colIdx, callback )
	{
		var col = settings.aoColumns[ colIdx ];
	
		_fnBindAction( attachTo, {}, function (e) {
			/* If the column is not sortable - don't to anything */
			if ( col.bSortable === false ) {
				return;
			}
	
			// If processing is enabled use a timeout to allow the processing
			// display to be shown - otherwise to it synchronously
			if ( settings.oFeatures.bProcessing ) {
				_fnProcessingDisplay( settings, true );
	
				setTimeout( function() {
					_fnSortListener( settings, colIdx, e.shiftKey, callback );
	
					// In server-side processing, the draw callback will remove the
					// processing display
					if ( _fnDataSource( settings ) !== 'ssp' ) {
						_fnProcessingDisplay( settings, false );
					}
				}, 0 );
			}
			else {
				_fnSortListener( settings, colIdx, e.shiftKey, callback );
			}
		} );
	}
Attach a sort handler (click) to a node
 @param {object} settings dataTables settings object
 @param {node} attachTo node to attach the handler to
 @param {int} colIdx column sorting index
 @param {function} [callback] callback function
 @memberof DataTable#oApi