    /**
     *
     */
    Ext.define('Ext.selection.CellModel', {
        extend: 'Ext.selection.Model',
        alias: 'selection.cellmodel',
        requires: ['Ext.util.KeyNav'],

        isCellModel: true,

        /**
         * @cfg {Boolean} enableKeyNav
         * Turns on/off keyboard navigation within the grid.
         */
        enableKeyNav: true,

        /**
         * @cfg {Boolean} preventWrap
         * Set this configuration to true to prevent wrapping around of selection as
         * a user navigates to the first or last column.
         */
        preventWrap: false,

        // private property to use when firing a deselect when no old selection exists.
        noSelection: {
            row: -1,
            column: -1
        },

        constructor: function() {
            this.addEvents(
                /**
                 * @event deselect
                 * Fired after a cell is deselected
                 * @param {Ext.selection.CellModel} this
                 * @param {Ext.data.Model} record The record of the deselected cell
                 * @param {Number} row The row index deselected
                 * @param {Number} column The column index deselected
                 */
                'deselect',

                /**
                 * @event select
                 * Fired after a cell is selected
                 * @param {Ext.selection.CellModel} this
                 * @param {Ext.data.Model} record The record of the selected cell
                 * @param {Number} row The row index selected
                 * @param {Number} column The column index selected
                 */
                'select'
            );
            this.callParent(arguments);
        },

        bindComponent: function(view) {
            var me = this,
                grid = view.ownerCt;
            me.primaryView = view;
            me.views = me.views || [];
            me.views.push(view);
            me.bindStore(view.getStore(), true);

            view.on({
                cellmousedown: me.onMouseDown,
                refresh: me.onViewRefresh,
                scope: me
            });
            if (grid.optimizedColumnMove !== false) {
                grid.on('columnmove', me.onColumnMove, me);
            }

            if (me.enableKeyNav) {
                me.initKeyNav(view);
            }
        },

        initKeyNav: function(view) {
            var me = this;

            if (!view.rendered) {
                view.on('render', Ext.Function.bind(me.initKeyNav, me, [view], 0), me, {single: true});
                return;
            }

            view.el.set({
                tabIndex: -1
            });

            // view.el has tabIndex -1 to allow for
            // keyboard events to be passed to it.
            me.keyNav = new Ext.util.KeyNav({
                target: view.el,
                ignoreInputFields: true,
                up: me.onKeyUp,
                down: me.onKeyDown,
                right: me.onKeyRight,
                left: me.onKeyLeft,
                tab: me.onKeyTab,
                scope: me
            });
        },

        getHeaderCt: function() {
            var selection = this.getCurrentPosition(),
                view = selection ? selection.view : this.primaryView;

            return view.headerCt;
        },

        onKeyUp: function(e, t) {
            this.keyNavigation = true;
            this.move('up', e);
            this.keyNavigation = false;
        },

        onKeyDown: function(e, t) {
            this.keyNavigation = true;
            this.move('down', e);
            this.keyNavigation = false;
        },

        onKeyLeft: function(e, t) {
            this.keyNavigation = true;
            this.move('left', e);
            this.keyNavigation = false;
        },

        onKeyRight: function(e, t) {
            this.keyNavigation = true;
            this.move('right', e);
            this.keyNavigation = false;
        },

        move: function(dir, e) {
            var me = this,
                pos = me.getCurrentPosition(),

                // Calculate the new row and column position
                newPos = pos.view.walkCells(pos, dir, e, me.preventWrap);

            // If walk was successful, select new Position
            if (newPos) {
                newPos.view = pos.view;
                return me.setCurrentPosition(newPos);
            }
            // <debug>
            // Enforce code correctness in unbuilt source.
            return null;
            // </debug>
        },

        /**
         * Returns the current position in the format {row: row, column: column}
         */
        getCurrentPosition: function() {
            return this.selection;
        },

        /**
         * Sets the current position
         * @param {Object} position The position to set.
         */
        setCurrentPosition: function(pos) {
            var me = this;

            // onSelectChange uses lastSelection and nextSelection
            me.lastSelection = me.selection;
            if (me.selection) {
                me.onCellDeselect(me.selection);
            }

            if (pos) {
                me.nextSelection = new me.Selection(me);
                me.nextSelection.setPosition(pos);
                me.onCellSelect(me.nextSelection);

                // Deselect triggered by new selection will kill the selection property, so restore it here.
                return me.selection = me.nextSelection;
            }
            // <debug>
            // Enforce code correctness in unbuilt source.
            return null;
            // </debug>
        },

        // Keep selection model in consistent state upon record deletion.
        onStoreRemove: function(store, record, index) {
            var me = this,
                pos = me.getCurrentPosition();

            me.callParent(arguments);
            if (pos) {
                // Deleting the row containing the selection.
                // Attempt to reselect the same cell which has moved up if there is one
                if (pos.row == index) {
                    if (index < store.getCount() - 1) {
                        pos.setPosition(index, pos.column);
                        me.setCurrentPosition(pos);
                    } else {
                        delete me.selection;
                    }
                }
                // Deleting a row before the selection.
                // Move the selection up by one row
                else if (index < pos.row) {
                    pos.setPosition(pos.row - 1, pos.column);
                    me.setCurrentPosition(pos);
                }
            }
        },

        /**
         * Set the current position based on where the user clicks.
         * @private
         */
        onMouseDown: function(view, cell, cellIndex, record, row, rowIndex, e) {
            this.setCurrentPosition({
                view: view,
                row: rowIndex,
                column: cellIndex
            });
        },

        // notify the view that the cell has been selected to update the ui
        // appropriately and bring the cell into focus
        onCellSelect: function(position, supressEvent) {
            if (position && position.row !== undefined && position.row > -1) {
                this.doSelect(position.view.getStore().getAt(position.row), /*keepExisting*/false, supressEvent);
            }
        },

        // notify view that the cell has been deselected to update the ui
        // appropriately
        onCellDeselect: function(position, supressEvent) {
            if (position && position.row !== undefined) {
                this.doDeselect(position.view.getStore().getAt(position.row), supressEvent);
            }
        },

        onSelectChange: function(record, isSelected, suppressEvent, commitFn) {
            var me = this,
                pos,
                eventName,
                view;

            if (isSelected) {
                pos = me.nextSelection;
                eventName = 'select';
            } else {
                pos = me.lastSelection || me.noSelection;
                eventName = 'deselect';
            }

            // CellModel may be shared between two sides of a Lockable.
            // The position must include a reference to the view in which the selection is current.
            // Ensure we use the view specifiied by the position.
            view = pos.view || me.primaryView;

            if ((suppressEvent || me.fireEvent('before' + eventName, me, record, pos.row, pos.column)) !== false &&
                    commitFn() !== false) {

                if (isSelected) {
                    view.onCellSelect(pos);
                    view.onCellFocus(pos);
                } else {
                    view.onCellDeselect(pos);
                    delete me.selection;
                }

                if (!suppressEvent) {
                    me.fireEvent(eventName, me, record, pos.row, pos.column);
                }
            }
        },

        // Tab key from the View's KeyNav, *not* from an editor.
        onKeyTab: function(e, t) {
            var me = this,
                editingPlugin = me.getCurrentPosition().view.editingPlugin;

            // If we were in editing mode, but just focused on a non-editable cell, behave as if we tabbed off an editable field
            if (editingPlugin && me.wasEditing) {
                me.onEditorTab(editingPlugin, e)
            } else {
                me.move(e.shiftKey ? 'left' : 'right', e);
            }
        },

        onEditorTab: function(editingPlugin, e) {
            var me = this,
                direction = e.shiftKey ? 'left' : 'right',
                position  = me.move(direction, e);

            // Navigation had somewhere to go.... not hit the buffers.
            if (position) {
                // If we were able to begin editing clear the wasEditing flag. It gets set during navigation off an active edit.
                if (editingPlugin.startEditByPosition(position)) {
                    me.wasEditing = false;
                }
                // If we could not continue editing...
                // Set a flag that we should go back into editing mode upon next onKeyTab call
                else {
                    me.wasEditing = true;
                    if (!position.columnHeader.dataIndex) {
                        me.onEditorTab(editingPlugin, e);
                    }
                }
            }
        },

        refresh: function() {
            var pos = this.getCurrentPosition(),
                selRowIdx;

            // Synchronize the current position's row with the row of the last selected record.
            if (pos && (selRowIdx = this.store.indexOf(this.selected.last())) !== -1) {
                pos.row = selRowIdx;
            }
        },

        /**
         * @private
         * When grid uses {@link Ext.panel.Table#optimizedColumnMove optimizedColumnMove} (the default), this is added as a
         * {@link Ext.panel.Table#columnmove columnmove} handler to correctly maintain the
         * selected column using the same column header.
         *
         * If optimizedColumnMove === false, (which some grid Features set) then the view is refreshed,
         * so this is not added as a handler because the selected column.
         */
        onColumnMove: function(headerCt, header, fromIdx, toIdx) {
            var grid = headerCt.up('tablepanel');
            if (grid) {
                this.onViewRefresh(grid.view);
            }
        },

        onViewRefresh: function(view) {
            var me = this,
                pos = me.getCurrentPosition(),
                headerCt = view.headerCt,
                record, columnHeader;

            // Re-establish selection of the same cell coordinate.
            // DO NOT fire events because the selected
            if (pos && pos.view === view) {
                record = pos.record;
                columnHeader = pos.columnHeader;

                // After a refresh, recreate the selection using the same record and grid column as before
                if (!columnHeader.isDescendantOf(headerCt)) {
                    // column header is not a child of the header container
                    // this happens when the grid is reconfigured with new columns
                    // make a best effor to select something by matching on id, then text, then dataIndex
                    columnHeader = headerCt.queryById(columnHeader.id) ||
                                   headerCt.down('[text="' + columnHeader.text + '"]') ||
                                   headerCt.down('[dataIndex="' + columnHeader.dataIndex + '"]');
                }

                // If we have a columnHeader (either the column header that already exists in
                // the headerCt, or a suitable match that was found after reconfiguration)
                // AND the record still exists in the store (or a record matching the id of
                // the previously selected record) We are ok to go ahead and set the selection
                if (columnHeader && (view.store.indexOfId(record.getId()) !== -1)) {
                    me.setCurrentPosition({
                        row: record,
                        column: columnHeader,
                        view: view
                    });
                }
            }
        },

        selectByPosition: function(position) {
            this.setCurrentPosition(position);
        }
    }, function() {

        // Encapsulate a single selection position.
        // Maintains { row: n, column: n, record: r, columnHeader: c}
        var Selection = this.prototype.Selection = function(model) {
            this.model = model;
        };
        // Selection row/record & column/columnHeader
        Selection.prototype.setPosition = function(row, col) {
            var me = this,
                view;

            // We were passed {row: 1, column: 2, view: myView}
            if (arguments.length === 1) {

                // SelectionModel is shared between both sides of a locking grid.
                // It can be positioned on either view.
                if (row.view) {
                    me.view = view = row.view;
                }
                col = row.column;
                row = row.row;
            }

            // If setting the position without specifying a view, and the position is already without a view
            // use the owning Model's primary view
            if (!view) {
                me.view = view = me.model.primaryView;
            }

            // Row index passed
            if (typeof row === 'number') {
                me.row = row;
                me.record = view.store.getAt(row);
            }
            // row is a Record
            else if (row.isModel) {
                me.record = row;
                me.row = view.indexOf(row);
            }
            // row is a grid row
            else if (row.tagName) {
                me.record = view.getRecord(row);
                me.row = view.indexOf(me.record);
            }

            // column index passed
            if (typeof col === 'number') {
                me.column = col;
                me.columnHeader = view.getHeaderAtIndex(col);
            }
            // col is a column Header
            else {
                me.columnHeader = col;
                me.column = col.getIndex();
            }
            return me;
        }
    });