The source code

    /**
     * @class Ext.layout.ToolbarLayout
     * @extends Ext.layout.ContainerLayout
     * Layout manager implicitly used by Ext.Toolbar.
     */
    Ext.layout.ToolbarLayout = Ext.extend(Ext.layout.ContainerLayout, {
        monitorResize : true,
        triggerWidth : 18,
        lastOverflow : false,

        noItemsMenuText : '(None)',
        // private
        onLayout : function(ct, target){
            if(!this.leftTr){
                target.addClass('x-toolbar-layout-ct');
                target.insertHtml('beforeEnd',
                     '');
                this.leftTr = target.child('tr.x-toolbar-left-row', true);
                this.rightTr = target.child('tr.x-toolbar-right-row', true);
                this.extrasTr = target.child('tr.x-toolbar-extras-row', true);
            }
            var side = this.leftTr;
            var pos = 0;

            var items = ct.items.items;
            for(var i = 0, len = items.length, c; i < len; i++, pos++) {
                c = items[i];
                if(c.isFill){
                    side = this.rightTr;
                    pos = -1;
                }else if(!c.rendered){
                    c.render(this.insertCell(c, side, pos));
                }else{
                    if(!c.xtbHidden && !this.isValidParent(c, side.childNodes[pos])){
                        var td = this.insertCell(c, side, pos);
                        td.appendChild(c.getDomPositionEl().dom);
                        c.container = Ext.get(td);
                    }
                }
            }
            //strip extra empty cells
            this.cleanup(this.leftTr);
            this.cleanup(this.rightTr);
            this.cleanup(this.extrasTr);
            this.fitToSize(target);
        },

        cleanup : function(row){
            var cn = row.childNodes;
            for(var i = cn.length-1, c; i >= 0 && (c = cn[i]); i--){
                if(!c.firstChild){
                    row.removeChild(c);
                }
            }
        },

        insertCell : function(c, side, pos){
            var td = document.createElement('td');
            td.className='x-toolbar-cell';
            side.insertBefore(td, side.childNodes[pos]||null);
            return td;
        },

        hideItem : function(item){
            var h = (this.hiddens = this.hiddens || []);
            h.push(item);
            item.xtbHidden = true;
            item.xtbWidth = item.getDomPositionEl().dom.parentNode.offsetWidth;
            item.hide();
        },

        unhideItem : function(item){
            item.show();
            item.xtbHidden = false;
            this.hiddens.remove(item);
            if(this.hiddens.length < 1){
                delete this.hiddens;
            }
        },

        getItemWidth : function(c){
            return c.hidden ? (c.xtbWidth || 0) : c.getDomPositionEl().dom.parentNode.offsetWidth;
        },

        fitToSize : function(t){
            if(this.container.enableOverflow === false){
                return;
            }
            var w = t.dom.clientWidth;
            var lw = this.lastWidth || 0;
            this.lastWidth = w;
            var iw = t.dom.firstChild.offsetWidth;

            var clipWidth = w - this.triggerWidth;
            var hideIndex = -1;

            if(iw > w || (this.hiddens && w >= lw)){
                var i, items = this.container.items.items, len = items.length, c;
                var loopWidth = 0;
                for(i = 0; i < len; i++) {
                    c = items[i];
                    if(!c.isFill){
                        loopWidth += this.getItemWidth(c);
                        if(loopWidth > clipWidth){
                            if(!c.xtbHidden){
                                this.hideItem(c);
                            }
                        }else{
                            if(c.xtbHidden){
                                this.unhideItem(c);
                            }
                        }
                    }
                }
            }
            if(this.hiddens){
                this.initMore();
                if(!this.lastOverflow){
                    this.container.fireEvent('overflowchange', this.container, true);
                    this.lastOverflow = true;
                }
            }else if(this.more){
                this.clearMenu();
                this.more.destroy();
                delete this.more;
                if(this.lastOverflow){
                    this.container.fireEvent('overflowchange', this.container, false);
                    this.lastOverflow = false;
                }
            }
        },

        createMenuConfig : function(c, hideOnClick){
            var cfg = Ext.apply({}, c.initialConfig),
                group = c.toggleGroup;

            Ext.apply(cfg, {
                text: c.overflowText || c.text,
                iconCls: c.iconCls,
                icon: c.icon,
                itemId: c.itemId,
                disabled: c.disabled,
                handler: c.handler,
                scope: c.scope,
                menu: c.menu,
                hideOnClick: hideOnClick
            });
            if(group || c.enableToggle){
                Ext.apply(cfg, {
                    group: group,
                    checked: c.pressed,
                    listeners: {
                        checkchange: function(item, checked){
                            c.toggle(checked);
                        }
                    }
                });
            }
            delete cfg.xtype;
            delete cfg.id;
            return cfg;
        },

        // private
        addComponentToMenu : function(m, c){
            if(c instanceof Ext.Toolbar.Separator){
                m.add('-');
            }else if(Ext.isFunction(c.isXType)){
                if(c.isXType('splitbutton')){
                    m.add(this.createMenuConfig(c, true));
                }else if(c.isXType('button')){
                    m.add(this.createMenuConfig(c, !c.menu));
                }else if(c.isXType('buttongroup')){
                    c.items.each(function(item){
                         this.addComponentToMenu(m, item);
                    }, this);
                }
            }
        },

        clearMenu : function(){
            var m = this.moreMenu;
            if(m && m.items){
                this.moreMenu.items.each(function(item){
                    delete item.menu;
                });
            }
        },

        // private
        beforeMoreShow : function(m){
            var h = this.container.items.items,
                len = h.length,
                c,
                prev,
                needsSep = function(group, item){
                    return group.isXType('buttongroup') && !(item instanceof Ext.Toolbar.Separator);
                };

            this.clearMenu();
            m.removeAll();
            for(var i = 0; i < len; i++){
                c = h[i];
                if(c.xtbHidden){
                    if(prev && (needsSep(c, prev) || needsSep(prev, c))){
                        m.add('-');
                    }
                    this.addComponentToMenu(m, c);
                    prev = c;
                }
            }
            // put something so the menu isn't empty
            // if no compatible items found
            if(m.items.length < 1){
                m.add(this.noItemsMenuText);
            }
        },

        initMore : function(){
            if(!this.more){
                this.moreMenu = new Ext.menu.Menu({
                    listeners: {
                        beforeshow: this.beforeMoreShow,
                        scope: this
                    }
                });
                this.more = new Ext.Button({
                    iconCls: 'x-toolbar-more-icon',
                    cls: 'x-toolbar-more',
                    menu: this.moreMenu
                });
                var td = this.insertCell(this.more, this.extrasTr, 100);
                this.more.render(td);
            }
        },

        destroy : function(){
            Ext.destroy(this.more, this.moreMenu);
            Ext.layout.ToolbarLayout.superclass.destroy.call(this);
        }
        /**
         * @property activeItem
         * @hide
         */
    });

    Ext.Container.LAYOUTS.toolbar = Ext.layout.ToolbarLayout;

    /**
     * @class Ext.Toolbar
     * @extends Ext.Container
     * Basic Toolbar class. Although the {@link Ext.Container#defaultType defaultType} for Toolbar
     * is {@link Ext.Button button}, Toolbar elements (child items for the Toolbar container) may
     * be virtually any type of Component. Toolbar elements can be created explicitly via their constructors,
     * or implicitly via their xtypes, and can be {@link #add}ed dynamically.
     * Some items have shortcut strings for creation:
     *
    Shortcut  xtype          Class                  Description
    '->'      'tbfill'       {@link Ext.Toolbar.Fill}       begin using the right-justified button container
    '-'       'tbseparator'  {@link Ext.Toolbar.Separator}  add a vertical separator bar between toolbar items
    ' '       'tbspacer'     {@link Ext.Toolbar.Spacer}     add horiztonal space between elements
     *
     *
     * Example usage of various elements:
     *
    var tb = new Ext.Toolbar({
        renderTo: document.body,
        width: 600,
        height: 100,
        items: [
            {
                // xtype: 'button', // default for Toolbars, same as 'tbbutton'
                text: 'Button'
            },
            {
                xtype: 'splitbutton', // same as 'tbsplitbutton'
                text: 'Split Button'
            },
            // begin using the right-justified button container
            '->', // same as {xtype: 'tbfill'}, // Ext.Toolbar.Fill
            {
                xtype: 'textfield',
                name: 'field1',
                emptyText: 'enter search term'
            },
            // add a vertical separator bar between toolbar items
            '-', // same as {xtype: 'tbseparator'} to create Ext.Toolbar.Separator
            'text 1', // same as {xtype: 'tbtext', text: 'text1'} to create Ext.Toolbar.TextItem
            {xtype: 'tbspacer'},// same as ' ' to create Ext.Toolbar.Spacer
            'text 2',
            {xtype: 'tbspacer', width: 50}, // add a 50px space
            'text 3'
        ]
    });
     *
     * Example adding a ComboBox within a menu of a button:
     *
    // ComboBox creation
    var combo = new Ext.form.ComboBox({
        store: new Ext.data.ArrayStore({
            autoDestroy: true,
            fields: ['initials', 'fullname'],
            data : [
                ['FF', 'Fred Flintstone'],
                ['BR', 'Barney Rubble']
            ]
        }),
        displayField: 'fullname',
        typeAhead: true,
        mode: 'local',
        forceSelection: true,
        triggerAction: 'all',
        emptyText: 'Select a name...',
        selectOnFocus: true,
        width: 135,
        getListParent: function() {
            return this.el.up('.x-menu');
        },
        iconCls: 'no-icon' //use iconCls if placing within menu to shift to right side of menu
    });

    // put ComboBox in a Menu
    var menu = new Ext.menu.Menu({
        id: 'mainMenu',
        items: [
            combo // A Field in a Menu
        ]
    });

    // add a Button with the menu
    tb.add({
            text:'Button w/ Menu',
            menu: menu  // assign menu by instance
        });
    tb.doLayout();
     *
     * @constructor
     * Creates a new Toolbar
     * @param {Object/Array} config A config object or an array of buttons to {@link #add}
     * @xtype toolbar
     */
    Ext.Toolbar = function(config){
        if(Ext.isArray(config)){
            config = {items: config, layout: 'toolbar'};
        } else {
            config = Ext.apply({
                layout: 'toolbar'
            }, config);
            if(config.buttons) {
                config.items = config.buttons;
            }
        }
        Ext.Toolbar.superclass.constructor.call(this, config);
    };

    (function(){

    var T = Ext.Toolbar;

    Ext.extend(T, Ext.Container, {

        defaultType: 'button',

        /**
         * @cfg {String/Object} layout
         * This class assigns a default layout (layout:'toolbar').
         * Developers may override this configuration option if another layout
         * is required (the constructor must be passed a configuration object in this
         * case instead of an array).
         * See {@link Ext.Container#layout} for additional information.
         */

        trackMenus : true,
        internalDefaults: {removeMode: 'container', hideParent: true},
        toolbarCls: 'x-toolbar',

        initComponent : function(){
            T.superclass.initComponent.call(this);

            /**
             * @event overflowchange
             * Fires after the overflow state has changed.
             * @param {Object} c The Container
             * @param {Boolean} lastOverflow overflow state
             */
            this.addEvents('overflowchange');
        },

        // private
        onRender : function(ct, position){
            if(!this.el){
                if(!this.autoCreate){
                    this.autoCreate = {
                        cls: this.toolbarCls + ' x-small-editor'
                    };
                }
                this.el = ct.createChild(Ext.apply({ id: this.id },this.autoCreate), position);
            }
        },

        /**
         * Adds element(s) to the toolbar -- this function takes a variable number of
         * arguments of mixed type and adds them to the toolbar.
         *
    Note: See the notes within {@link Ext.Container#add}.
         * @param {Mixed} arg1 The following types of arguments are all valid:

         *
         * {@link Ext.Button} config: A valid button config object (equivalent to {@link #addButton})
         * HtmlElement: Any standard HTML element (equivalent to {@link #addElement})
         * Field: Any form field (equivalent to {@link #addField})
         * Item: Any subclass of {@link Ext.Toolbar.Item} (equivalent to {@link #addItem})
         * String: Any generic string (gets wrapped in a {@link Ext.Toolbar.TextItem}, equivalent to {@link #addText}).
         * Note that there are a few special strings that are treated differently as explained next.
         * '-': Creates a separator element (equivalent to {@link #addSeparator})
         * ' ': Creates a spacer element (equivalent to {@link #addSpacer})
         * '->': Creates a fill element (equivalent to {@link #addFill})
         *
         * @param {Mixed} arg2
         * @param {Mixed} etc.
         * @method add
         */

        // private
        lookupComponent : function(c){
            if(Ext.isString(c)){
                if(c == '-'){
                    c = new T.Separator();
                }else if(c == ' '){
                    c = new T.Spacer();
                }else if(c == '->'){
                    c = new T.Fill();
                }else{
                    c = new T.TextItem(c);
                }
                this.applyDefaults(c);
            }else{
                if(c.isFormField || c.render){ // some kind of form field, some kind of Toolbar.Item
                    c = this.constructItem(c);
                }else if(c.tag){ // DomHelper spec
                    c = new T.Item({autoEl: c});
                }else if(c.tagName){ // element
                    c = new T.Item({el:c});
                }else if(Ext.isObject(c)){ // must be button config?
                    c = c.xtype ? this.constructItem(c) : this.constructButton(c);
                }
            }
            return c;
        },

        // private
        applyDefaults : function(c){
            if(!Ext.isString(c)){
                c = Ext.Toolbar.superclass.applyDefaults.call(this, c);
                var d = this.internalDefaults;
                if(c.events){
                    Ext.applyIf(c.initialConfig, d);
                    Ext.apply(c, d);
                }else{
                    Ext.applyIf(c, d);
                }
            }
            return c;
        },

        // private
        constructItem : function(item, type){
            return Ext.create(item, type || this.defaultType);
        },

        /**
         * Adds a separator
         *
    Note: See the notes within {@link Ext.Container#add}.
         * @return {Ext.Toolbar.Item} The separator {@link Ext.Toolbar.Item item}
         */
        addSeparator : function(){
            return this.add(new T.Separator());
        },

        /**
         * Adds a spacer element
         *
    Note: See the notes within {@link Ext.Container#add}.
         * @return {Ext.Toolbar.Spacer} The spacer item
         */
        addSpacer : function(){
            return this.add(new T.Spacer());
        },

        /**
         * Forces subsequent additions into the float:right toolbar
         *
    Note: See the notes within {@link Ext.Container#add}.
         */
        addFill : function(){
            this.add(new T.Fill());
        },

        /**
         * Adds any standard HTML element to the toolbar
         *
    Note: See the notes within {@link Ext.Container#add}.
         * @param {Mixed} el The element or id of the element to add
         * @return {Ext.Toolbar.Item} The element's item
         */
        addElement : function(el){
            return this.addItem(new T.Item({el:el}));
        },

        /**
         * Adds any Toolbar.Item or subclass
         *
    Note: See the notes within {@link Ext.Container#add}.
         * @param {Ext.Toolbar.Item} item
         * @return {Ext.Toolbar.Item} The item
         */
        addItem : function(item){
            return Ext.Toolbar.superclass.add.apply(this, arguments);
        },

        /**
         * Adds a button (or buttons). See {@link Ext.Button} for more info on the config.
         *
    Note: See the notes within {@link Ext.Container#add}.
         * @param {Object/Array} config A button config or array of configs
         * @return {Ext.Button/Array}
         */
        addButton : function(config){
            if(Ext.isArray(config)){
                var buttons = [];
                for(var i = 0, len = config.length; i < len; i++) {
                    buttons.push(this.addButton(config[i]));
                }
                return buttons;
            }
            return this.add(this.constructButton(config));
        },

        /**
         * Adds text to the toolbar
         *
    Note: See the notes within {@link Ext.Container#add}.
         * @param {String} text The text to add
         * @return {Ext.Toolbar.Item} The element's item
         */
        addText : function(text){
            return this.addItem(new T.TextItem(text));
        },

        /**
         * Adds a new element to the toolbar from the passed {@link Ext.DomHelper} config
         *
    Note: See the notes within {@link Ext.Container#add}.
         * @param {Object} config
         * @return {Ext.Toolbar.Item} The element's item
         */
        addDom : function(config){
            return this.add(new T.Item({autoEl: config}));
        },

        /**
         * Adds a dynamically rendered Ext.form field (TextField, ComboBox, etc). Note: the field should not have
         * been rendered yet. For a field that has already been rendered, use {@link #addElement}.
         *
    Note: See the notes within {@link Ext.Container#add}.
         * @param {Ext.form.Field} field
         * @return {Ext.Toolbar.Item}
         */
        addField : function(field){
            return this.add(field);
        },

        /**
         * Inserts any {@link Ext.Toolbar.Item}/{@link Ext.Button} at the specified index.
         *
    Note: See the notes within {@link Ext.Container#add}.
         * @param {Number} index The index where the item is to be inserted
         * @param {Object/Ext.Toolbar.Item/Ext.Button/Array} item The button, or button config object to be
         * inserted, or an array of buttons/configs.
         * @return {Ext.Button/Item}
         */
        insertButton : function(index, item){
            if(Ext.isArray(item)){
                var buttons = [];
                for(var i = 0, len = item.length; i < len; i++) {
                   buttons.push(this.insertButton(index + i, item[i]));
                }
                return buttons;
            }
            return Ext.Toolbar.superclass.insert.call(this, index, item);
        },

        // private
        initMenuTracking : function(item){
            if(this.trackMenus && item.menu){
                this.mon(item, {
                    'menutriggerover' : this.onButtonTriggerOver,
                    'menushow' : this.onButtonMenuShow,
                    'menuhide' : this.onButtonMenuHide,
                    scope: this
                });
            }
        },

        // private
        constructButton : function(item){
            var b = item.events ? item : this.constructItem(item, item.split ? 'splitbutton' : this.defaultType);
            this.initMenuTracking(b);
            return b;
        },

        // private
        onDisable : function(){
            this.items.each(function(item){
                 if(item.disable){
                     item.disable();
                 }
            });
        },

        // private
        onEnable : function(){
            this.items.each(function(item){
                 if(item.enable){
                     item.enable();
                 }
            });
        },

        // private
        onButtonTriggerOver : function(btn){
            if(this.activeMenuBtn && this.activeMenuBtn != btn){
                this.activeMenuBtn.hideMenu();
                btn.showMenu();
                this.activeMenuBtn = btn;
            }
        },

        // private
        onButtonMenuShow : function(btn){
            this.activeMenuBtn = btn;
        },

        // private
        onButtonMenuHide : function(btn){
            delete this.activeMenuBtn;
        }
    });
    Ext.reg('toolbar', Ext.Toolbar);

    /**
     * @class Ext.Toolbar.Item
     * @extends Ext.BoxComponent
     * The base class that other non-interacting Toolbar Item classes should extend in order to
     * get some basic common toolbar item functionality.
     * @constructor
     * Creates a new Item
     * @param {HTMLElement} el
     * @xtype tbitem
     */
    T.Item = Ext.extend(Ext.BoxComponent, {
        hideParent: true, //  Hiding a Toolbar.Item hides its containing TD
        enable:Ext.emptyFn,
        disable:Ext.emptyFn,
        focus:Ext.emptyFn
        /**
         * @cfg {String} overflowText Text to be used for the menu if the item is overflowed.
         */
    });
    Ext.reg('tbitem', T.Item);

    /**
     * @class Ext.Toolbar.Separator
     * @extends Ext.Toolbar.Item
     * A simple class that adds a vertical separator bar between toolbar items
     * (css class:'xtb-sep'). Example usage:
     *
    new Ext.Panel({
        tbar : [
            'Item 1',
            {xtype: 'tbseparator'}, // or '-'
            'Item 2'
        ]
    });

     * @constructor
     * Creates a new Separator
     * @xtype tbseparator
     */
    T.Separator = Ext.extend(T.Item, {
        onRender : function(ct, position){
            this.el = ct.createChild({tag:'span', cls:'xtb-sep'}, position);
        }
    });
    Ext.reg('tbseparator', T.Separator);

    /**
     * @class Ext.Toolbar.Spacer
     * @extends Ext.Toolbar.Item
     * A simple element that adds extra horizontal space between items in a toolbar.
     * By default a 2px wide space is added via css specification:
    .x-toolbar .xtb-spacer {
        width:2px;
    }
     *
     * Example usage:
     *
    new Ext.Panel({
        tbar : [
            'Item 1',
            {xtype: 'tbspacer'}, // or ' '
            'Item 2',
            // space width is also configurable via javascript
            {xtype: 'tbspacer', width: 50}, // add a 50px space
            'Item 3'
        ]
    });

     * @constructor
     * Creates a new Spacer
     * @xtype tbspacer
     */
    T.Spacer = Ext.extend(T.Item, {
        /**
         * @cfg {Number} width
         * The width of the spacer in pixels (defaults to 2px via css style .x-toolbar .xtb-spacer).
         */

        onRender : function(ct, position){
            this.el = ct.createChild({tag:'div', cls:'xtb-spacer', style: this.width?'width:'+this.width+'px':''}, position);
        }
    });
    Ext.reg('tbspacer', T.Spacer);

    /**
     * @class Ext.Toolbar.Fill
     * @extends Ext.Toolbar.Spacer
     * A non-rendering placeholder item which instructs the Toolbar's Layout to begin using
     * the right-justified button container.
     *
    new Ext.Panel({
        tbar : [
            'Item 1',
            {xtype: 'tbfill'}, // or '->'
            'Item 2'
        ]
    });

     * @constructor
     * Creates a new Fill
     * @xtype tbfill
     */
    T.Fill = Ext.extend(T.Item, {
        // private
        render : Ext.emptyFn,
        isFill : true
    });
    Ext.reg('tbfill', T.Fill);

    /**
     * @class Ext.Toolbar.TextItem
     * @extends Ext.Toolbar.Item
     * A simple class that renders text directly into a toolbar
     * (with css class:'xtb-text'). Example usage:
     *
    new Ext.Panel({
        tbar : [
            {xtype: 'tbtext', text: 'Item 1'} // or simply 'Item 1'
        ]
    });

     * @constructor
     * Creates a new TextItem
     * @param {String/Object} text A text string, or a config object containing a text property
     * @xtype tbtext
     */
    T.TextItem = Ext.extend(T.Item, {
        constructor: function(config){
            if (Ext.isString(config)) {
                config = { autoEl: {cls: 'xtb-text', html: config }};
            } else {
                config.autoEl = {cls: 'xtb-text', html: config.text || ''};
            }
            T.TextItem.superclass.constructor.call(this, config);
        },
        /**
         * Updates this item's text, setting the text to be used as innerHTML.
         * @param {String} t The text to display (html accepted).
         */
        setText : function(t) {
            if (this.rendered) {
                this.el.dom.innerHTML = t;
            } else {
                this.autoEl.html = t;
            }
        }
    });
    Ext.reg('tbtext', T.TextItem);

    // backwards compat
    T.Button = Ext.extend(Ext.Button, {});
    T.SplitButton = Ext.extend(Ext.SplitButton, {});
    Ext.reg('tbbutton', T.Button);
    Ext.reg('tbsplit', T.SplitButton);

    })();