    /**
     * @class Ext.grid.plugin.CellEditing
     * @extends Ext.grid.plugin.Editing
     *
     * The Ext.grid.plugin.CellEditing plugin injects editing at a cell level for a Grid. Only a single
     * cell will be editable at a time. The field that will be used for the editor is defined at the
     * {@link Ext.grid.column.Column#field field}. The editor can be a field instance or a field configuration.
     *
     * If an editor is not specified for a particular column then that cell will not be editable and it will
     * be skipped when activated via the mouse or the keyboard.
     *
     * The editor may be shared for each column in the grid, or a different one may be specified for each column.
     * An appropriate field type should be chosen to match the data structure that it will be editing. For example,
     * to edit a date, it would be useful to specify {@link Ext.form.field.Date} as the editor.
     *
     * {@img Ext.grid.plugin.CellEditing/Ext.grid.plugin.CellEditing.png Ext.grid.plugin.CellEditing plugin}
     *
     * ## Example Usage
     *
     *     Ext.create('Ext.data.Store', {
     *         storeId:'simpsonsStore',
     *         fields:['name', 'email', 'phone'],
     *         data:{'items':[
     *             {"name":"Lisa", "email":"lisa@simpsons.com", "phone":"555-111-1224"},
     *             {"name":"Bart", "email":"bart@simpsons.com", "phone":"555--222-1234"},
     *             {"name":"Homer", "email":"home@simpsons.com", "phone":"555-222-1244"},
     *             {"name":"Marge", "email":"marge@simpsons.com", "phone":"555-222-1254"}
     *         ]},
     *         proxy: {
     *             type: 'memory',
     *             reader: {
     *                 type: 'json',
     *                 root: 'items'
     *             }
     *         }
     *     });
     *
     *     Ext.create('Ext.grid.Panel', {
     *         title: 'Simpsons',
     *         store: Ext.data.StoreManager.lookup('simpsonsStore'),
     *         columns: [
     *             {header: 'Name',  dataIndex: 'name', field: 'textfield'},
     *             {header: 'Email', dataIndex: 'email', flex:1,
     *                 editor: {
     *                     xtype:'textfield',
     *                     allowBlank:false
     *                 }
     *             },
     *             {header: 'Phone', dataIndex: 'phone'}
     *         ],
     *         selType: 'cellmodel',
     *         plugins: [
     *             Ext.create('Ext.grid.plugin.CellEditing', {
     *                 clicksToEdit: 1
     *             })
     *         ],
     *         height: 200,
     *         width: 400,
     *         renderTo: Ext.getBody()
     *     });
     */
    Ext.define('Ext.grid.plugin.CellEditing', {
        alias: 'plugin.cellediting',
        extend: 'Ext.grid.plugin.Editing',
        requires: ['Ext.grid.CellEditor'],

        constructor: function() {
            /**
             * @event beforeedit
             * Fires before cell editing is triggered. The edit event object has the following properties <br />
             * <ul style="padding:5px;padding-left:16px;">
             * <li>grid - The grid</li>
             * <li>record - The record being edited</li>
             * <li>field - The field name being edited</li>
             * <li>value - The value for the field being edited.</li>
             * <li>row - The grid table row</li>
             * <li>column - The grid {@link Ext.grid.column.Column Column} defining the column that is being edited.</li>
             * <li>rowIdx - The row index that is being edited</li>
             * <li>colIdx - The column index that is being edited</li>
             * <li>cancel - Set this to true to cancel the edit or return false from your handler.</li>
             * </ul>
             * @param {Ext.grid.plugin.Editing} editor
             * @param {Object} e An edit event (see above for description)
             */
            /**
             * @event edit
             * Fires after a cell is edited. The edit event object has the following properties <br />
             * <ul style="padding:5px;padding-left:16px;">
             * <li>grid - The grid</li>
             * <li>record - The record that was edited</li>
             * <li>field - The field name that was edited</li>
             * <li>value - The value being set</li>
             * <li>originalValue - The original value for the field, before the edit.</li>
             * <li>row - The grid table row</li>
             * <li>column - The grid {@link Ext.grid.column.Column Column} defining the column that was edited.</li>
             * <li>rowIdx - The row index that was edited</li>
             * <li>colIdx - The column index that was edited</li>
             * </ul>
             *
             * <pre><code>
    grid.on('edit', onEdit, this);

    function onEdit(e) {
        // execute an XHR to send/commit data to the server, in callback do (if successful):
        e.record.commit();
    };
             * </code></pre>
             * @param {Ext.grid.plugin.Editing} editor
             * @param {Object} e An edit event (see above for description)
             */
            /**
             * @event validateedit
             * Fires after a cell is edited, but before the value is set in the record. Return false
             * to cancel the change. The edit event object has the following properties <br />
             * <ul style="padding:5px;padding-left:16px;">
             * <li>grid - The grid</li>
             * <li>record - The record being edited</li>
             * <li>field - The field name being edited</li>
             * <li>value - The value being set</li>
             * <li>originalValue - The original value for the field, before the edit.</li>
             * <li>row - The grid table row</li>
             * <li>column - The grid {@link Ext.grid.column.Column Column} defining the column that is being edited.</li>
             * <li>rowIdx - The row index that is being edited</li>
             * <li>colIdx - The column index that is being edited</li>
             * <li>cancel - Set this to true to cancel the edit or return false from your handler.</li>
             * </ul>
             * Usage example showing how to remove the red triangle (dirty record indicator) from some
             * records (not all).  By observing the grid's validateedit event, it can be cancelled if
             * the edit occurs on a targeted row (for example) and then setting the field's new value
             * in the Record directly:
             * <pre><code>
    grid.on('validateedit', function(e) {
      var myTargetRow = 6;

      if (e.row == myTargetRow) {
        e.cancel = true;
        e.record.data[e.field] = e.value;
      }
    });
             * </code></pre>
             * @param {Ext.grid.plugin.Editing} editor
             * @param {Object} e An edit event (see above for description)
             */
            this.callParent(arguments);
            this.editors = Ext.create('Ext.util.MixedCollection', false, function(editor) {
                return editor.editorId;
            });
        },

        /**
         * @private
         * AbstractComponent calls destroy on all its plugins at destroy time.
         */
        destroy: function() {
            var me = this;
            me.editors.each(Ext.destroy, Ext);
            me.editors.clear();
            me.callParent(arguments);
        },

        // private
        // Template method called from base class's initEvents
        initCancelTriggers: function() {
            var me   = this;
                grid = me.grid,
                view   = grid.view;

            me.mon(view, {
                mousewheel: {
                    element: 'el',
                    fn: me.cancelEdit,
                    scope: me
                }
            });
            me.mon(grid, {
                columnresize: me.cancelEdit,
                columnmove: me.cancelEdit,
                scope: me
            });
        },

        /**
         * Start editing the specified record, using the specified Column definition to define which field is being edited.
         * @param {Model} record The Store data record which backs the row to be edited.
         * @param {Model} columnHeader The Column object defining the column to be edited.
         * @override
         */
        startEdit: function(record, columnHeader) {
            var me = this,
                ed   = me.getEditor(record, columnHeader),
                value = record.get(columnHeader.dataIndex),
                context = me.getEditingContext(record, columnHeader);

            record = context.record;
            columnHeader = context.column;

            // Complete the edit now, before getting the editor's target
            // cell DOM element. Completing the edit causes a view refresh.
            me.completeEdit();

            // See if the field is editable for the requested record
            if (columnHeader && !columnHeader.getEditor(record)) {
                return false;
            }

            if (ed) {
                context.originalValue = context.value = value;
                if (me.beforeEdit(context) === false || me.fireEvent('beforeedit', context) === false || context.cancel) {
                    return false;
                }

                me.context = context;
                me.setActiveEditor(ed);
                me.setActiveRecord(record);
                me.setActiveColumn(columnHeader);

                // Defer, so we have some time between view scroll to sync up the editor
                Ext.defer(ed.startEdit, 15, ed, [me.getCell(record, columnHeader), value]);
            } else {
                // BrowserBug: WebKit & IE refuse to focus the element, rather
                // it will focus it and then immediately focus the body. This
                // temporary hack works for Webkit and IE6. IE7 and 8 are still
                // broken
                me.grid.getView().el.focus((Ext.isWebKit || Ext.isIE) ? 10 : false);
            }
        },

        completeEdit: function() {
            var activeEd = this.getActiveEditor();
            if (activeEd) {
                activeEd.completeEdit();
            }
        },

        // internal getters/setters
        setActiveEditor: function(ed) {
            this.activeEditor = ed;
        },

        getActiveEditor: function() {
            return this.activeEditor;
        },

        setActiveColumn: function(column) {
            this.activeColumn = column;
        },

        getActiveColumn: function() {
            return this.activeColumn;
        },

        setActiveRecord: function(record) {
            this.activeRecord = record;
        },

        getActiveRecord: function() {
            return this.activeRecord;
        },

        getEditor: function(record, column) {
            var editors = this.editors,
                editorId = column.itemId || column.id,
                editor = editors.getByKey(editorId);

            if (editor) {
                return editor;
            } else {
                editor = column.getEditor(record);
                if (!editor) {
                    return false;
                }

                // Allow them to specify a CellEditor in the Column
                if (!(editor instanceof Ext.grid.CellEditor)) {
                    editor = Ext.create('Ext.grid.CellEditor', {
                        editorId: editorId,
                        field: editor
                    });
                }
                editor.parentEl = this.grid.getEditorParent();
                // editor.parentEl should be set here.
                editor.on({
                    scope: this,
                    specialkey: this.onSpecialKey,
                    complete: this.onEditComplete,
                    canceledit: this.cancelEdit
                });
                editors.add(editor);
                return editor;
            }
        },

        /**
         * Get the cell (td) for a particular record and column.
         * @param {Ext.data.Model} record
         * @param {Ext.grid.column.Colunm} column
         * @private
         */
        getCell: function(record, column) {
            return this.grid.getView().getCell(record, column);
        },

        onSpecialKey: function(ed, field, e) {
            var grid = this.grid,
                sm;
            if (e.getKey() === e.TAB) {
                e.stopEvent();
                sm = grid.getSelectionModel();
                if (sm.onEditorTab) {
                    sm.onEditorTab(this, e);
                }
            }
        },

        onEditComplete : function(ed, value, startValue) {
            var me = this,
                grid = me.grid,
                sm = grid.getSelectionModel(),
                dataIndex = me.getActiveColumn().dataIndex;

            me.setActiveEditor(null);
            me.setActiveColumn(null);
            me.setActiveRecord(null);
            delete sm.wasEditing;

            if (!me.validateEdit()) {
                return;
            }
            me.context.record.set(dataIndex, value);
            me.fireEvent('edit', me, me.context);
        },

        /**
         * Cancel any active editing.
         */
        cancelEdit: function() {
            var me = this,
                activeEd = me.getActiveEditor(),
                viewEl = me.grid.getView().el;

            me.setActiveEditor(null);
            me.setActiveColumn(null);
            me.setActiveRecord(null);
            if (activeEd) {
                activeEd.cancelEdit();
                viewEl.focus();
            }
        },

        /**
         * Starts editing by position (row/column)
         * @param {Object} position A position with keys of row and column.
         */
        startEditByPosition: function(position) {
            var me = this,
                grid = me.grid,
                sm = grid.getSelectionModel(),
                editRecord = grid.store.getAt(position.row),
                editColumnHeader = grid.headerCt.getHeaderAtIndex(position.column);

            if (sm.selectByPosition) {
                sm.selectByPosition(position);
            }
            me.startEdit(editRecord, editColumnHeader);
        }
    });