The source code

    /**
     * @class Ext.grid.Column
     * <p>This class encapsulates column configuration data to be used in the initialization of a
     * {@link Ext.grid.ColumnModel ColumnModel}.</p>
     * <p>While subclasses are provided to render data in different ways, this class renders a passed
     * data field unchanged and is usually used for textual columns.</p>
     */
    Ext.grid.Column = Ext.extend(Ext.util.Observable, {
        /**
         * @cfg {Boolean} editable Optional. Defaults to <tt>true</tt>, enabling the configured
         * <tt>{@link #editor}</tt>.  Set to <tt>false</tt> to initially disable editing on this column.
         * The initial configuration may be dynamically altered using
         * {@link Ext.grid.ColumnModel}.{@link Ext.grid.ColumnModel#setEditable setEditable()}.
         */
        /**
         * @cfg {String} id Optional. A name which identifies this column (defaults to the column's initial
         * ordinal position.) The <tt>id</tt> is used to create a CSS <b>class</b> name which is applied to all
         * table cells (including headers) in that column (in this context the <tt>id</tt> does not need to be
         * unique). The class name takes the form of <pre>x-grid3-td-<b>id</b></pre>
         * Header cells will also receive this class name, but will also have the class <pre>x-grid3-hd</pre>
         * So, to target header cells, use CSS selectors such as:<pre>.x-grid3-hd-row .x-grid3-td-<b>id</b></pre>
         * The {@link Ext.grid.GridPanel#autoExpandColumn} grid config option references the column via this
         * unique identifier.
         */
        /**
         * @cfg {String} header Optional. The header text to be used as innerHTML
         * (html tags are accepted) to display in the Grid view.  <b>Note</b>: to
         * have a clickable header with no text displayed use <tt>'&amp;#160;'</tt>.
         */
        /**
         * @cfg {Boolean} groupable Optional. If the grid is being rendered by an {@link Ext.grid.GroupingView}, this option
         * may be used to disable the header menu item to group by the column selected. Defaults to <tt>true</tt>,
         * which enables the header menu group option.  Set to <tt>false</tt> to disable (but still show) the
         * group option in the header menu for the column. See also <code>{@link #groupName}</code>.
         */
        /**
         * @cfg {String} groupName Optional. If the grid is being rendered by an {@link Ext.grid.GroupingView}, this option
         * may be used to specify the text with which to prefix the group field value in the group header line.
         * See also {@link #groupRenderer} and
         * {@link Ext.grid.GroupingView}.{@link Ext.grid.GroupingView#showGroupName showGroupName}.
         */
        /**
         * @cfg {Function} groupRenderer <p>Optional. If the grid is being rendered by an {@link Ext.grid.GroupingView}, this option
         * may be used to specify the function used to format the grouping field value for display in the group
         * {@link #groupName header}.  If a <tt><b>groupRenderer</b></tt> is not specified, the configured
         * <tt><b>{@link #renderer}</b></tt> will be called; if a <tt><b>{@link #renderer}</b></tt> is also not specified
         * the new value of the group field will be used.</p>
         * <p>The called function (either the <tt><b>groupRenderer</b></tt> or <tt><b>{@link #renderer}</b></tt>) will be
         * passed the following parameters:
         * <div class="mdetail-params"><ul>
         * <li><b>v</b> : Object<p class="sub-desc">The new value of the group field.</p></li>
         * <li><b>unused</b> : undefined<p class="sub-desc">Unused parameter.</p></li>
         * <li><b>r</b> : Ext.data.Record<p class="sub-desc">The Record providing the data
         * for the row which caused group change.</p></li>
         * <li><b>rowIndex</b> : Number<p class="sub-desc">The row index of the Record which caused group change.</p></li>
         * <li><b>colIndex</b> : Number<p class="sub-desc">The column index of the group field.</p></li>
         * <li><b>ds</b> : Ext.data.Store<p class="sub-desc">The Store which is providing the data Model.</p></li>
         * </ul></div></p>
         * <p>The function should return a string value.</p>
         */
        /**
         * @cfg {String} emptyGroupText Optional. If the grid is being rendered by an {@link Ext.grid.GroupingView}, this option
         * may be used to specify the text to display when there is an empty group value. Defaults to the
         * {@link Ext.grid.GroupingView}.{@link Ext.grid.GroupingView#emptyGroupText emptyGroupText}.
         */
        /**
         * @cfg {String} dataIndex <p><b>Required</b>. The name of the field in the
         * grid's {@link Ext.data.Store}'s {@link Ext.data.Record} definition from
         * which to draw the column's value.</p>
         */
        /**
         * @cfg {Number} width
         * Optional. The initial width in pixels of the column.
         * The width of each column can also be affected if any of the following are configured:
         * <div class="mdetail-params"><ul>
         * <li>{@link Ext.grid.GridPanel}.<tt>{@link Ext.grid.GridPanel#autoExpandColumn autoExpandColumn}</tt></li>
         * <li>{@link Ext.grid.GridView}.<tt>{@link Ext.grid.GridView#forceFit forceFit}</tt>
         * <div class="sub-desc">
         * <p>By specifying <tt>forceFit:true</tt>, {@link #fixed non-fixed width} columns will be
         * re-proportioned (based on the relative initial widths) to fill the width of the grid so
         * that no horizontal scrollbar is shown.</p>
         * </div></li>
         * <li>{@link Ext.grid.GridView}.<tt>{@link Ext.grid.GridView#autoFill autoFill}</tt></li>
         * <li>{@link Ext.grid.GridPanel}.<tt>{@link Ext.grid.GridPanel#minColumnWidth minColumnWidth}</tt></li>
         * <br><p><b>Note</b>: when the width of each column is determined, a space on the right side
         * is reserved for the vertical scrollbar.  The
         * {@link Ext.grid.GridView}.<tt>{@link Ext.grid.GridView#scrollOffset scrollOffset}</tt>
         * can be modified to reduce or eliminate the reserved offset.</p>
         */
        /**
         * @cfg {Boolean} sortable Optional. <tt>true</tt> if sorting is to be allowed on this column.
         * Defaults to the value of the <code>{@link Ext.grid.ColumnModel#defaultSortable}</code> property.
         * Whether local/remote sorting is used is specified in <code>{@link Ext.data.Store#remoteSort}</code>.
         */
        /**
         * @cfg {Boolean} fixed Optional. <tt>true</tt> if the column width cannot be changed.  Defaults to <tt>false</tt>.
         */
        /**
         * @cfg {Boolean} resizable Optional. <tt>false</tt> to disable column resizing. Defaults to <tt>true</tt>.
         */
        /**
         * @cfg {Boolean} menuDisabled Optional. <tt>true</tt> to disable the column menu. Defaults to <tt>false</tt>.
         */
        /**
         * @cfg {Boolean} hidden
         * Optional. <tt>true</tt> to initially hide this column. Defaults to <tt>false</tt>.
         * A hidden column {@link Ext.grid.GridPanel#enableColumnHide may be shown via the header row menu}.
         * If a column is never to be shown, simply do not include this column in the Column Model at all.
         */
        /**
         * @cfg {String} tooltip Optional. A text string to use as the column header's tooltip.  If Quicktips
         * are enabled, this value will be used as the text of the quick tip, otherwise it will be set as the
         * header's HTML title attribute. Defaults to ''.
         */
        /**
         * @cfg {Mixed} renderer
         * <p>For an alternative to specifying a renderer see <code>{@link #xtype}</code></p>
         * <p>Optional. A renderer is an 'interceptor' method which can be used transform data (value,
         * appearance, etc.) before it is rendered). This may be specified in either of three ways:
         * <div class="mdetail-params"><ul>
         * <li>A renderer function used to return HTML markup for a cell given the cell's data value.</li>
         * <li>A string which references a property name of the {@link Ext.util.Format} class which
         * provides a renderer function.</li>
         * <li>An object specifying both the renderer function, and its execution scope (<tt><b>this</b></tt>
         * reference) e.g.:<pre style="margin-left:1.2em"><code>
    {
        fn: this.gridRenderer,
        scope: this
    }
    </code></pre></li></ul></div>
         * If not specified, the default renderer uses the raw data value.</p>
         * <p>For information about the renderer function (passed parameters, etc.), see
         * {@link Ext.grid.ColumnModel#setRenderer}. An example of specifying renderer function inline:</p><pre><code>
    var companyColumn = {
       header: 'Company Name',
       dataIndex: 'company',
       renderer: function(value, metaData, record, rowIndex, colIndex, store) {
          // provide the logic depending on business rules
          // name of your own choosing to manipulate the cell depending upon
          // the data in the underlying Record object.
          if (value == 'whatever') {
              //metaData.css : String : A CSS class name to add to the TD element of the cell.
              //metaData.attr : String : An html attribute definition string to apply to
              //                         the data container element within the table
              //                         cell (e.g. 'style="color:red;"').
              metaData.css = 'name-of-css-class-you-will-define';
          }
          return value;
       }
    }
         * </code></pre>
         * See also {@link #scope}.
         */
        /**
         * @cfg {String} xtype Optional. A String which references a predefined {@link Ext.grid.Column} subclass
         * type which is preconfigured with an appropriate <code>{@link #renderer}</code> to be easily
         * configured into a ColumnModel. The predefined {@link Ext.grid.Column} subclass types are:
         * <div class="mdetail-params"><ul>
         * <li><b><tt>gridcolumn</tt></b> : {@link Ext.grid.Column} (<b>Default</b>)<p class="sub-desc"></p></li>
         * <li><b><tt>booleancolumn</tt></b> : {@link Ext.grid.BooleanColumn}<p class="sub-desc"></p></li>
         * <li><b><tt>numbercolumn</tt></b> : {@link Ext.grid.NumberColumn}<p class="sub-desc"></p></li>
         * <li><b><tt>datecolumn</tt></b> : {@link Ext.grid.DateColumn}<p class="sub-desc"></p></li>
         * <li><b><tt>templatecolumn</tt></b> : {@link Ext.grid.TemplateColumn}<p class="sub-desc"></p></li>
         * </ul></div>
         * <p>Configuration properties for the specified <code>xtype</code> may be specified with
         * the Column configuration properties, for example:</p>
         * <pre><code>
    var grid = new Ext.grid.GridPanel({
        ...
        columns: [{
            header: 'Last Updated',
            dataIndex: 'lastChange',
            width: 85,
            sortable: true,
            //renderer: Ext.util.Format.dateRenderer('m/d/Y'),
            xtype: 'datecolumn', // use xtype instead of renderer
            format: 'M/d/Y' // configuration property for {@link Ext.grid.DateColumn}
        }, {
            ...
        }]
    });
         * </code></pre>
         */
        /**
         * @cfg {Object} scope Optional. The scope (<tt><b>this</b></tt> reference) in which to execute the
         * renderer.  Defaults to the Column configuration object.
         */
        /**
         * @cfg {String} align Optional. Set the CSS text-align property of the column.  Defaults to undefined.
         */
        /**
         * @cfg {String} css Optional. An inline style definition string which is applied to all table cells in the column
         * (excluding headers). Defaults to undefined.
         */
        /**
         * @cfg {Boolean} hideable Optional. Specify as <tt>false</tt> to prevent the user from hiding this column
         * (defaults to true).  To disallow column hiding globally for all columns in the grid, use
         * {@link Ext.grid.GridPanel#enableColumnHide} instead.
         */
        /**
         * @cfg {Ext.form.Field} editor Optional. The {@link Ext.form.Field} to use when editing values in this column
         * if editing is supported by the grid. See <tt>{@link #editable}</tt> also.
         */

        /**
         * @private
         * @cfg {Boolean} isColumn
         * Used by ColumnModel setConfig method to avoid reprocessing a Column
         * if <code>isColumn</code> is not set ColumnModel will recreate a new Ext.grid.Column
         * Defaults to true.
         */
        isColumn : true,

        constructor : function(config){
            Ext.apply(this, config);

            if(Ext.isString(this.renderer)){
                this.renderer = Ext.util.Format[this.renderer];
            }else if(Ext.isObject(this.renderer)){
                this.scope = this.renderer.scope;
                this.renderer = this.renderer.fn;
            }
            if(!this.scope){
                this.scope = this;
            }

            var ed = this.editor;
            delete this.editor;
            this.setEditor(ed);
            this.addEvents(
                /**
                 * @event click
                 * Fires when this Column is clicked.
                 * @param {Column} this
                 * @param {Grid} The owning GridPanel
                 * @param {Number} rowIndex
                 * @param {Ext.EventObject} e
                 */
                'click',
                /**
                 * @event contextmenu
                 * Fires when this Column is right clicked.
                 * @param {Column} this
                 * @param {Grid} The owning GridPanel
                 * @param {Number} rowIndex
                 * @param {Ext.EventObject} e
                 */
                'contextmenu',
                /**
                 * @event dblclick
                 * Fires when this Column is double clicked.
                 * @param {Column} this
                 * @param {Grid} The owning GridPanel
                 * @param {Number} rowIndex
                 * @param {Ext.EventObject} e
                 */
                'dblclick',
                /**
                 * @event mousedown
                 * Fires when this Column receives a mousedown event.
                 * @param {Column} this
                 * @param {Grid} The owning GridPanel
                 * @param {Number} rowIndex
                 * @param {Ext.EventObject} e
                 */
                'mousedown'
            );
            Ext.grid.Column.superclass.constructor.call(this);
        },

        /**
         * @private
         * Process and refire events routed from the GridView's processEvent method.
         * Returns the event handler's status to allow cancelling of GridView's bubbling process.
         */
        processEvent : function(name, e, grid, rowIndex, colIndex){
            return this.fireEvent(name, this, grid, rowIndex, e);
        },

        /**
         * @private
         * Clean up. Remove any Editor. Remove any listeners.
         */
        destroy: function() {
            if(this.setEditor){
                this.setEditor(null);
            }
            this.purgeListeners();
        },

        /**
         * Optional. A function which returns displayable data when passed the following parameters:
         * <div class="mdetail-params"><ul>
         * <li><b>value</b> : Object<p class="sub-desc">The data value for the cell.</p></li>
         * <li><b>metadata</b> : Object<p class="sub-desc">An object in which you may set the following attributes:<ul>
         * <li><b>css</b> : String<p class="sub-desc">A CSS class name to add to the cell's TD element.</p></li>
         * <li><b>attr</b> : String<p class="sub-desc">An HTML attribute definition string to apply to the data container
         * element <i>within</i> the table cell (e.g. 'style="color:red;"').</p></li></ul></p></li>
         * <li><b>record</b> : Ext.data.record<p class="sub-desc">The {@link Ext.data.Record} from which the data was
         * extracted.</p></li>
         * <li><b>rowIndex</b> : Number<p class="sub-desc">Row index</p></li>
         * <li><b>colIndex</b> : Number<p class="sub-desc">Column index</p></li>
         * <li><b>store</b> : Ext.data.Store<p class="sub-desc">The {@link Ext.data.Store} object from which the Record
         * was extracted.</p></li>
         * </ul></div>
         * @property renderer
         * @type Function
         */
        renderer : function(value){
            return value;
        },

        // private
        getEditor: function(rowIndex){
            return this.editable !== false ? this.editor : null;
        },

        /**
         * Sets a new editor for this column.
         * @param {Ext.Editor/Ext.form.Field} editor The editor to set
         */
        setEditor : function(editor){
            var ed = this.editor;
            if(ed){
                if(ed.gridEditor){
                    ed.gridEditor.destroy();
                    delete ed.gridEditor;
                }else{
                    ed.destroy();
                }
            }
            this.editor = null;
            if(editor){
                //not an instance, create it
                if(!editor.isXType){
                    editor = Ext.create(editor, 'textfield');
                }
                this.editor = editor;
            }
        },

        /**
         * Returns the {@link Ext.Editor editor} defined for this column that was created to wrap the {@link Ext.form.Field Field}
         * used to edit the cell.
         * @param {Number} rowIndex The row index
         * @return {Ext.Editor}
         */
        getCellEditor: function(rowIndex){
            var ed = this.getEditor(rowIndex);
            if(ed){
                if(!ed.startEdit){
                    if(!ed.gridEditor){
                        ed.gridEditor = new Ext.grid.GridEditor(ed);
                    }
                    ed = ed.gridEditor;
                }
            }
            return ed;
        }
    });

    /**
     * @class Ext.grid.BooleanColumn
     * @extends Ext.grid.Column
     * <p>A Column definition class which renders boolean data fields.  See the {@link Ext.grid.Column#xtype xtype}
     * config option of {@link Ext.grid.Column} for more details.</p>
     */
    Ext.grid.BooleanColumn = Ext.extend(Ext.grid.Column, {
        /**
         * @cfg {String} trueText
         * The string returned by the renderer when the column value is not falsy (defaults to <tt>'true'</tt>).
         */
        trueText: 'true',
        /**
         * @cfg {String} falseText
         * The string returned by the renderer when the column value is falsy (but not undefined) (defaults to
         * <tt>'false'</tt>).
         */
        falseText: 'false',
        /**
         * @cfg {String} undefinedText
         * The string returned by the renderer when the column value is undefined (defaults to <tt>'&amp;#160;'</tt>).
         */
        undefinedText: '&#160;',

        constructor: function(cfg){
            Ext.grid.BooleanColumn.superclass.constructor.call(this, cfg);
            var t = this.trueText, f = this.falseText, u = this.undefinedText;
            this.renderer = function(v){
                if(v === undefined){
                    return u;
                }
                if(!v || v === 'false'){
                    return f;
                }
                return t;
            };
        }
    });

    /**
     * @class Ext.grid.NumberColumn
     * @extends Ext.grid.Column
     * <p>A Column definition class which renders a numeric data field according to a {@link #format} string.  See the
     * {@link Ext.grid.Column#xtype xtype} config option of {@link Ext.grid.Column} for more details.</p>
     */
    Ext.grid.NumberColumn = Ext.extend(Ext.grid.Column, {
        /**
         * @cfg {String} format
         * A formatting string as used by {@link Ext.util.Format#number} to format a numeric value for this Column
         * (defaults to <tt>'0,000.00'</tt>).
         */
        format : '0,000.00',
        constructor: function(cfg){
            Ext.grid.NumberColumn.superclass.constructor.call(this, cfg);
            this.renderer = Ext.util.Format.numberRenderer(this.format);
        }
    });

    /**
     * @class Ext.grid.DateColumn
     * @extends Ext.grid.Column
     * <p>A Column definition class which renders a passed date according to the default locale, or a configured
     * {@link #format}. See the {@link Ext.grid.Column#xtype xtype} config option of {@link Ext.grid.Column}
     * for more details.</p>
     */
    Ext.grid.DateColumn = Ext.extend(Ext.grid.Column, {
        /**
         * @cfg {String} format
         * A formatting string as used by {@link Date#format} to format a Date for this Column
         * (defaults to <tt>'m/d/Y'</tt>).
         */
        format : 'm/d/Y',
        constructor: function(cfg){
            Ext.grid.DateColumn.superclass.constructor.call(this, cfg);
            this.renderer = Ext.util.Format.dateRenderer(this.format);
        }
    });

    /**
     * @class Ext.grid.TemplateColumn
     * @extends Ext.grid.Column
     * <p>A Column definition class which renders a value by processing a {@link Ext.data.Record Record}'s
     * {@link Ext.data.Record#data data} using a {@link #tpl configured} {@link Ext.XTemplate XTemplate}.
     * See the {@link Ext.grid.Column#xtype xtype} config option of {@link Ext.grid.Column} for more
     * details.</p>
     */
    Ext.grid.TemplateColumn = Ext.extend(Ext.grid.Column, {
        /**
         * @cfg {String/XTemplate} tpl
         * An {@link Ext.XTemplate XTemplate}, or an XTemplate <i>definition string</i> to use to process a
         * {@link Ext.data.Record Record}'s {@link Ext.data.Record#data data} to produce a column's rendered value.
         */
        constructor: function(cfg){
            Ext.grid.TemplateColumn.superclass.constructor.call(this, cfg);
            var tpl = (!Ext.isPrimitive(this.tpl) && this.tpl.compile) ? this.tpl : new Ext.XTemplate(this.tpl);
            this.renderer = function(value, p, r){
                return tpl.apply(r.data);
            };
            this.tpl = tpl;
        }
    });

    /**
     * @class Ext.grid.ActionColumn
     * @extends Ext.grid.Column
     * <p>A Grid column type which renders an icon, or a series of icons in a grid cell, and offers a scoped click
     * handler for each icon. Example usage:</p>
    <pre><code>
    new Ext.grid.GridPanel({
        store: myStore,
        columns: [
            {
                xtype: 'actioncolumn',
                width: 50,
                items: [
                    {
                        icon   : 'sell.gif',                // Use a URL in the icon config
                        tooltip: 'Sell stock',
                        handler: function(grid, rowIndex, colIndex) {
                            var rec = store.getAt(rowIndex);
                            alert("Sell " + rec.get('company'));
                        }
                    },
                    {
                        getClass: function(v, meta, rec) {  // Or return a class from a function
                            if (rec.get('change') < 0) {
                                this.items[1].tooltip = 'Do not buy!';
                                return 'alert-col';
                            } else {
                                this.items[1].tooltip = 'Buy stock';
                                return 'buy-col';
                            }
                        },
                        handler: function(grid, rowIndex, colIndex) {
                            var rec = store.getAt(rowIndex);
                            alert("Buy " + rec.get('company'));
                        }
                    }
                ]
            }
            //any other columns here
        ]
    });
    </pre></code>
     * <p>The action column can be at any index in the columns array, and a grid can have any number of
     * action columns. </p>
     */
    Ext.grid.ActionColumn = Ext.extend(Ext.grid.Column, {
        /**
         * @cfg {String} icon
         * The URL of an image to display as the clickable element in the column.
         * Optional - defaults to <code>{@link Ext#BLANK_IMAGE_URL Ext.BLANK_IMAGE_URL}</code>.
         */
        /**
         * @cfg {String} iconCls
         * A CSS class to apply to the icon image. To determine the class dynamically, configure the Column with a <code>{@link #getClass}</code> function.
         */
        /**
         * @cfg {Function} handler A function called when the icon is clicked.
         * The handler is passed the following parameters:<div class="mdetail-params"><ul>
         * <li><code>grid</code> : GridPanel<div class="sub-desc">The owning GridPanel.</div></li>
         * <li><code>rowIndex</code> : Number<div class="sub-desc">The row index clicked on.</div></li>
         * <li><code>colIndex</code> : Number<div class="sub-desc">The column index clicked on.</div></li>
         * <li><code>item</code> : Object<div class="sub-desc">The clicked item (or this Column if multiple
         * {@link #items} were not configured).</div></li>
         * <li><code>e</code> : Event<div class="sub-desc">The click event.</div></li>
         * </ul></div>
         */
        /**
         * @cfg {Object} scope The scope (<tt><b>this</b></tt> reference) in which the <code>{@link #handler}</code>
         * and <code>{@link #getClass}</code> fuctions are executed. Defaults to this Column.
         */
        /**
         * @cfg {String} tooltip A tooltip message to be displayed on hover. {@link Ext.QuickTips#init Ext.QuickTips} must have
         * been initialized.
         */
        /**
         * @cfg {Boolean} stopSelection Defaults to <code>true</code>. Prevent grid <i>row</i> selection upon mousedown.
         */
        /**
         * @cfg {Function} getClass A function which returns the CSS class to apply to the icon image.
         * The function is passed the following parameters:<div class="mdetail-params"><ul>
         *     <li><b>v</b> : Object<p class="sub-desc">The value of the column's configured field (if any).</p></li>
         *     <li><b>metadata</b> : Object<p class="sub-desc">An object in which you may set the following attributes:<ul>
         *         <li><b>css</b> : String<p class="sub-desc">A CSS class name to add to the cell's TD element.</p></li>
         *         <li><b>attr</b> : String<p class="sub-desc">An HTML attribute definition string to apply to the data container element <i>within</i> the table cell
         *         (e.g. 'style="color:red;"').</p></li>
         *     </ul></p></li>
         *     <li><b>r</b> : Ext.data.Record<p class="sub-desc">The Record providing the data.</p></li>
         *     <li><b>rowIndex</b> : Number<p class="sub-desc">The row index..</p></li>
         *     <li><b>colIndex</b> : Number<p class="sub-desc">The column index.</p></li>
         *     <li><b>store</b> : Ext.data.Store<p class="sub-desc">The Store which is providing the data Model.</p></li>
         * </ul></div>
         */
        /**
         * @cfg {Array} items An Array which may contain multiple icon definitions, each element of which may contain:
         * <div class="mdetail-params"><ul>
         * <li><code>icon</code> : String<div class="sub-desc">The url of an image to display as the clickable element
         * in the column.</div></li>
         * <li><code>iconCls</code> : String<div class="sub-desc">A CSS class to apply to the icon image.
         * To determine the class dynamically, configure the item with a <code>getClass</code> function.</div></li>
         * <li><code>getClass</code> : Function<div class="sub-desc">A function which returns the CSS class to apply to the icon image.
         * The function is passed the following parameters:<ul>
         *     <li><b>v</b> : Object<p class="sub-desc">The value of the column's configured field (if any).</p></li>
         *     <li><b>metadata</b> : Object<p class="sub-desc">An object in which you may set the following attributes:<ul>
         *         <li><b>css</b> : String<p class="sub-desc">A CSS class name to add to the cell's TD element.</p></li>
         *         <li><b>attr</b> : String<p class="sub-desc">An HTML attribute definition string to apply to the data container element <i>within</i> the table cell
         *         (e.g. 'style="color:red;"').</p></li>
         *     </ul></p></li>
         *     <li><b>r</b> : Ext.data.Record<p class="sub-desc">The Record providing the data.</p></li>
         *     <li><b>rowIndex</b> : Number<p class="sub-desc">The row index..</p></li>
         *     <li><b>colIndex</b> : Number<p class="sub-desc">The column index.</p></li>
         *     <li><b>store</b> : Ext.data.Store<p class="sub-desc">The Store which is providing the data Model.</p></li>
         * </ul></div></li>
         * <li><code>handler</code> : Function<div class="sub-desc">A function called when the icon is clicked.</div></li>
         * <li><code>scope</code> : Scope<div class="sub-desc">The scope (<code><b>this</b></code> reference) in which the
         * <code>handler</code> and <code>getClass</code> functions are executed. Fallback defaults are this Column's
         * configured scope, then this Column.</div></li>
         * <li><code>tooltip</code> : String<div class="sub-desc">A tooltip message to be displayed on hover.
         * {@link Ext.QuickTips#init Ext.QuickTips} must have been initialized.</div></li>
         * </ul></div>
         */
        header: '&#160;',

        actionIdRe: /x-action-col-(\d+)/,

        /**
         * @cfg {String} altText The alt text to use for the image element. Defaults to <tt>''</tt>.
         */
        altText: '',

        constructor: function(cfg) {
            var me = this,
                items = cfg.items || (me.items = [me]),
                l = items.length,
                i,
                item;

            Ext.grid.ActionColumn.superclass.constructor.call(me, cfg);

    //      Renderer closure iterates through items creating an <img> element for each and tagging with an identifying
    //      class name x-action-col-{n}
            me.renderer = function(v, meta) {
    //          Allow a configured renderer to create initial value (And set the other values in the "metadata" argument!)
                v = Ext.isFunction(cfg.renderer) ? cfg.renderer.apply(this, arguments)||'' : '';

                meta.css += ' x-action-col-cell';
                for (i = 0; i < l; i++) {
                    item = items[i];
                    v += '<img alt="' + (item.altText || me.altText) + '" src="' + (item.icon || Ext.BLANK_IMAGE_URL) +
                        '" class="x-action-col-icon x-action-col-' + String(i) + ' ' + (item.iconCls || '') +
                        ' ' + (Ext.isFunction(item.getClass) ? item.getClass.apply(item.scope||this.scope||this, arguments) : '') + '"' +
                        ((item.tooltip) ? ' ext:qtip="' + item.tooltip + '"' : '') + ' />';
                }
                return v;
            };
        },

        destroy: function() {
            delete this.items;
            delete this.renderer;
            return Ext.grid.ActionColumn.superclass.destroy.apply(this, arguments);
        },

        /**
         * @private
         * Process and refire events routed from the GridView's processEvent method.
         * Also fires any configured click handlers. By default, cancels the mousedown event to prevent selection.
         * Returns the event handler's status to allow cancelling of GridView's bubbling process.
         */
        processEvent : function(name, e, grid, rowIndex, colIndex){
            var m = e.getTarget().className.match(this.actionIdRe),
                item, fn;
            if (m && (item = this.items[parseInt(m[1], 10)])) {
                if (name == 'click') {
                    (fn = item.handler || this.handler) && fn.call(item.scope||this.scope||this, grid, rowIndex, colIndex, item, e);
                } else if ((name == 'mousedown') && (item.stopSelection !== false)) {
                    return false;
                }
            }
            return Ext.grid.ActionColumn.superclass.processEvent.apply(this, arguments);
        }
    });

    /*
     * @property types
     * @type Object
     * @member Ext.grid.Column
     * @static
     * <p>An object containing predefined Column classes keyed by a mnemonic code which may be referenced
     * by the {@link Ext.grid.ColumnModel#xtype xtype} config option of ColumnModel.</p>
     * <p>This contains the following properties</p><div class="mdesc-details"><ul>
     * <li>gridcolumn : <b>{@link Ext.grid.Column Column constructor}</b></li>
     * <li>booleancolumn : <b>{@link Ext.grid.BooleanColumn BooleanColumn constructor}</b></li>
     * <li>numbercolumn : <b>{@link Ext.grid.NumberColumn NumberColumn constructor}</b></li>
     * <li>datecolumn : <b>{@link Ext.grid.DateColumn DateColumn constructor}</b></li>
     * <li>templatecolumn : <b>{@link Ext.grid.TemplateColumn TemplateColumn constructor}</b></li>
     * </ul></div>
     */
    Ext.grid.Column.types = {
        gridcolumn : Ext.grid.Column,
        booleancolumn: Ext.grid.BooleanColumn,
        numbercolumn: Ext.grid.NumberColumn,
        datecolumn: Ext.grid.DateColumn,
        templatecolumn: Ext.grid.TemplateColumn,
        actioncolumn: Ext.grid.ActionColumn
    };