      *
      *  @param event The DragEvent object.
      * 
-     *  @see spark.layouts.LayoutBase#showDropIndicator
-     *  @see spark.layouts.LayoutBase#hideDropIndicator
+     *  @see spark.layouts.supportClasses.LayoutBase#showDropIndicator
+     *  @see spark.layouts.supportClasses.LayoutBase#hideDropIndicator
      *  
      *  @langversion 3.0
      *  @playerversion Flash 11

        if (rowIndex == -1 || isCellSelection && columnIndex == -1)
            return;


        if (event.ctrlKey)
        {
            // ctrl-click toggles the selection and updates caret and anchor.
            if (!toggleSelection(rowIndex, columnIndex))
                return;
            
            grid.anchorRowIndex = rowIndex;
            grid.anchorColumnIndex = columnIndex;
        }
        else
        {
            if (event.shiftKey)
            {
                // shift-click extends the selection and updates the caret.
                if  (grid.selectionMode == GridSelectionMode.MULTIPLE_ROWS || grid.selectionMode == GridSelectionMode.MULTIPLE_CELLS)
                {    
                    if (!extendSelection(rowIndex, columnIndex))
                        return;
                }
            }
            else
            {
                // click sets the selection and updates the caret and anchor positions.
                setSelectionAnchorCaret(rowIndex, columnIndex);
            }
        }


        if (dragEnabled && isRowSelectionMode() && selectionContainsIndex(rowIndex))
        {
            pendingSelectionOnMouseUp = true;
        }
        
        // If selection is pending on mouse up then we have just moused down on
        // an item, part of an already commited selection.
        // However if we moused down on an item that's not currently selected,

        mouseDownRowIndex = rowIndex;
        mouseDownColumnIndex = columnIndex;
        
        var listenForDrag:Boolean = dragEnabled &&
            getStyle("interactionMode") == InteractionMode.MOUSE && selectedIndices && 
            this.selectedIndices.indexOf(rowIndex) != -1;
        // Handle any drag gestures that may have been started
        if (listenForDrag)
        {
            // Listen for GRID_MOUSE_DRAG.
            // The user may have clicked on the item renderer close
            // to the edge of the list, and we still want to start a drag
            // operation if they move out of the list.
            grid.addEventListener(GridEvent.GRID_MOUSE_DRAG, grid_mouseDragHandler);
