The source code

    /*!
     * Ext JS Library 3.4.0
     * Copyright(c) 2006-2011 Sencha Inc.
     * licensing@sencha.com
     * http://www.sencha.com/license
     */
    /**
     * @class Ext.Button
     * @extends Ext.BoxComponent
     * Simple Button class
     * @cfg {String} text The button text to be used as innerHTML (html tags are accepted)
     * @cfg {String} icon The path to an image to display in the button (the image will be set as the background-image
     * CSS property of the button by default, so if you want a mixed icon/text button, set cls:'x-btn-text-icon')
     * @cfg {Function} handler A function called when the button is clicked (can be used instead of click event).
     * The handler is passed the following parameters:
     * b : ButtonThis Button.
     * e : EventObjectThe click event.
     *
     * @cfg {Number} minWidth The minimum width for this button (used to give a set of buttons a common width).
     * See also {@link Ext.Panel}.{@link Ext.Panel#minButtonWidth minButtonWidth}.
     * @cfg {String/Object} tooltip The tooltip for the button - can be a string to be used as innerHTML (html tags are accepted) or QuickTips config object
     * @cfg {Boolean} hidden True to start hidden (defaults to false)
     * @cfg {Boolean} disabled True to start disabled (defaults to false)
     * @cfg {Boolean} pressed True to start pressed (only if enableToggle = true)
     * @cfg {String} toggleGroup The group this toggle button is a member of (only 1 per group can be pressed)
     * @cfg {Boolean/Object} repeat True to repeat fire the click event while the mouse is down. This can also be
     * a {@link Ext.util.ClickRepeater ClickRepeater} config object (defaults to false).
     * @constructor
     * Create a new button
     * @param {Object} config The config object
     * @xtype button
     */
    Ext.Button = Ext.extend(Ext.BoxComponent, {
        /**
         * Read-only. True if this button is hidden
         * @type Boolean
         */
        hidden : false,
        /**
         * Read-only. True if this button is disabled
         * @type Boolean
         */
        disabled : false,
        /**
         * Read-only. True if this button is pressed (only if enableToggle = true)
         * @type Boolean
         */
        pressed : false,

        /**
         * @cfg {Number} tabIndex Set a DOM tabIndex for this button (defaults to undefined)
         */

        /**
         * @cfg {Boolean} allowDepress
         * False to not allow a pressed Button to be depressed (defaults to undefined). Only valid when {@link #enableToggle} is true.
         */

        /**
         * @cfg {Boolean} enableToggle
         * True to enable pressed/not pressed toggling (defaults to false)
         */
        enableToggle : false,
        /**
         * @cfg {Function} toggleHandler
         * Function called when a Button with {@link #enableToggle} set to true is clicked. Two arguments are passed:
         * button : Ext.Buttonthis Button object
         * state : BooleanThe next state of the Button, true means pressed.
         *
         */
        /**
         * @cfg {Mixed} menu
         * Standard menu attribute consisting of a reference to a menu object, a menu id or a menu config blob (defaults to undefined).
         */
        /**
         * @cfg {String} menuAlign
         * The position to align the menu to (see {@link Ext.Element#alignTo} for more details, defaults to 'tl-bl?').
         */
        menuAlign : 'tl-bl?',

        /**
         * @cfg {String} overflowText If used in a {@link Ext.Toolbar Toolbar}, the
         * text to be used if this item is shown in the overflow menu. See also
         * {@link Ext.Toolbar.Item}.{@link Ext.Toolbar.Item#overflowText overflowText}.
         */
        /**
         * @cfg {String} iconCls
         * A css class which sets a background image to be used as the icon for this button
         */
        /**
         * @cfg {String} type
         * submit, reset or button - defaults to 'button'
         */
        type : 'button',

        // private
        menuClassTarget : 'tr:nth(2)',

        /**
         * @cfg {String} clickEvent
         * The DOM event that will fire the handler of the button. This can be any valid event name (dblclick, contextmenu).
         * Defaults to 'click'.
         */
        clickEvent : 'click',

        /**
         * @cfg {Boolean} handleMouseEvents
         * False to disable visual cues on mouseover, mouseout and mousedown (defaults to true)
         */
        handleMouseEvents : true,

        /**
         * @cfg {String} tooltipType
         * The type of tooltip to use. Either 'qtip' (default) for QuickTips or 'title' for title attribute.
         */
        tooltipType : 'qtip',

        /**
         * @cfg {String} buttonSelector
         * (Optional) A {@link Ext.DomQuery DomQuery} selector which is used to extract the active, clickable element from the
         * DOM structure created.
         * When a custom {@link #template} is used, you  must ensure that this selector results in the selection of
         * a focussable element.
         * Defaults to 'button:first-child'.
         */
        buttonSelector : 'button:first-child',

        /**
         * @cfg {String} scale
         * (Optional) The size of the Button. Three values are allowed:
         *
         * 'small'Results in the button element being 16px high.
         * 'medium'Results in the button element being 24px high.
         * 'large'Results in the button element being 32px high.
         *
         * Defaults to 'small'.
         */
        scale : 'small',

        /**
         * @cfg {Object} scope The scope (this reference) in which the
         * {@link #handler} and {@link #toggleHandler} is
         * executed. Defaults to this Button.
         */

        /**
         * @cfg {String} iconAlign
         * (Optional) The side of the Button box to render the icon. Four values are allowed:
         *
         * 'top'
         * 'right'
         * 'bottom'
         * 'left'
         *
         * Defaults to 'left'.
         */
        iconAlign : 'left',

        /**
         * @cfg {String} arrowAlign
         * (Optional) The side of the Button box to render the arrow if the button has an associated {@link #menu}.
         * Two values are allowed:
         *
         * 'right'
         * 'bottom'
         *
         * Defaults to 'right'.
         */
        arrowAlign : 'right',

        /**
         * @cfg {Ext.Template} template (Optional)
         * A {@link Ext.Template Template} used to create the Button's DOM structure.
         * Instances, or subclasses which need a different DOM structure may provide a different
         * template layout in conjunction with an implementation of {@link #getTemplateArgs}.
         * @type Ext.Template
         * @property template
         */
        /**
         * @cfg {String} cls
         * A CSS class string to apply to the button's main element.
         */
        /**
         * @property menu
         * @type Menu
         * The {@link Ext.menu.Menu Menu} object associated with this Button when configured with the {@link #menu} config option.
         */
        /**
         * @cfg {Boolean} autoWidth
         * By default, if a width is not specified the button will attempt to stretch horizontally to fit its content.
         * If the button is being managed by a width sizing layout (hbox, fit, anchor), set this to false to prevent
         * the button from doing this automatic sizing.
         * Defaults to undefined.
         */

        initComponent : function(){
            if(this.menu){
                // If array of items, turn it into an object config so we
                // can set the ownerCt property in the config
                if (Ext.isArray(this.menu)){
                    this.menu = { items: this.menu };
                }

                // An object config will work here, but an instance of a menu
                // will have already setup its ref's and have no effect
                if (Ext.isObject(this.menu)){
                    this.menu.ownerCt = this;
                }

                this.menu = Ext.menu.MenuMgr.get(this.menu);
                this.menu.ownerCt = undefined;
            }

            Ext.Button.superclass.initComponent.call(this);

            this.addEvents(
                /**
                 * @event click
                 * Fires when this button is clicked
                 * @param {Button} this
                 * @param {EventObject} e The click event
                 */
                'click',
                /**
                 * @event toggle
                 * Fires when the 'pressed' state of this button changes (only if enableToggle = true)
                 * @param {Button} this
                 * @param {Boolean} pressed
                 */
                'toggle',
                /**
                 * @event mouseover
                 * Fires when the mouse hovers over the button
                 * @param {Button} this
                 * @param {Event} e The event object
                 */
                'mouseover',
                /**
                 * @event mouseout
                 * Fires when the mouse exits the button
                 * @param {Button} this
                 * @param {Event} e The event object
                 */
                'mouseout',
                /**
                 * @event menushow
                 * If this button has a menu, this event fires when it is shown
                 * @param {Button} this
                 * @param {Menu} menu
                 */
                'menushow',
                /**
                 * @event menuhide
                 * If this button has a menu, this event fires when it is hidden
                 * @param {Button} this
                 * @param {Menu} menu
                 */
                'menuhide',
                /**
                 * @event menutriggerover
                 * If this button has a menu, this event fires when the mouse enters the menu triggering element
                 * @param {Button} this
                 * @param {Menu} menu
                 * @param {EventObject} e
                 */
                'menutriggerover',
                /**
                 * @event menutriggerout
                 * If this button has a menu, this event fires when the mouse leaves the menu triggering element
                 * @param {Button} this
                 * @param {Menu} menu
                 * @param {EventObject} e
                 */
                'menutriggerout'
            );

            if(Ext.isString(this.toggleGroup)){
                this.enableToggle = true;
            }
        },

    /**
      * This method returns an Array which provides substitution parameters for the {@link #template Template} used
      * to create this Button's DOM structure.
      * Instances or subclasses which use a different Template to create a different DOM structure may need to provide their
      * own implementation of this method.
      * The default implementation which provides data for the default {@link #template} returns an Array containing the
      * following items:
      * The <button>'s {@link #type}
      * A CSS class name applied to the Button's main <tbody> element which determines the button's scale and icon alignment.
      * A CSS class to determine the presence and position of an arrow icon. ('x-btn-arrow' or 'x-btn-arrow-bottom' or '')
      * The {@link #cls} CSS class name applied to the button's wrapping <table> element.
      * The Component id which is applied to the button's wrapping <table> element.
      *
      * @return {Array} Substitution data for a Template.
     */
        getTemplateArgs : function(){
            return [this.type, 'x-btn-' + this.scale + ' x-btn-icon-' + this.scale + '-' + this.iconAlign, this.getMenuClass(), this.cls, this.id];
        },

        // private
        setButtonClass : function(){
            if(this.useSetClass){
                if(!Ext.isEmpty(this.oldCls)){
                    this.el.removeClass([this.oldCls, 'x-btn-pressed']);
                }
                this.oldCls = (this.iconCls || this.icon) ? (this.text ? 'x-btn-text-icon' : 'x-btn-icon') : 'x-btn-noicon';
                this.el.addClass([this.oldCls, this.pressed ? 'x-btn-pressed' : null]);
            }
        },

        // protected
        getMenuClass : function(){
            return this.menu ? (this.arrowAlign != 'bottom' ? 'x-btn-arrow' : 'x-btn-arrow-bottom') : '';
        },

        // private
        onRender : function(ct, position){
            if(!this.template){
                if(!Ext.Button.buttonTemplate){
                    // hideous table template
                    Ext.Button.buttonTemplate = new Ext.Template(
                        '',
                        '  ',
                        '  ',
                        '  ',
                        '');
                    Ext.Button.buttonTemplate.compile();
                }
                this.template = Ext.Button.buttonTemplate;
            }

            var btn, targs = this.getTemplateArgs();

            if(position){
                btn = this.template.insertBefore(position, targs, true);
            }else{
                btn = this.template.append(ct, targs, true);
            }
            /**
             * An {@link Ext.Element Element} encapsulating the Button's clickable element. By default,
             * this references a <button> element. Read only.
             * @type Ext.Element
             * @property btnEl
             */
            this.btnEl = btn.child(this.buttonSelector);
            this.mon(this.btnEl, {
                scope: this,
                focus: this.onFocus,
                blur: this.onBlur
            });

            this.initButtonEl(btn, this.btnEl);

            Ext.ButtonToggleMgr.register(this);
        },

        // private
        initButtonEl : function(btn, btnEl){
            this.el = btn;
            this.setIcon(this.icon);
            this.setText(this.text);
            this.setIconClass(this.iconCls);
            if(Ext.isDefined(this.tabIndex)){
                btnEl.dom.tabIndex = this.tabIndex;
            }
            if(this.tooltip){
                this.setTooltip(this.tooltip, true);
            }

            if(this.handleMouseEvents){
                this.mon(btn, {
                    scope: this,
                    mouseover: this.onMouseOver,
                    mousedown: this.onMouseDown
                });

                // new functionality for monitoring on the document level
                //this.mon(btn, 'mouseout', this.onMouseOut, this);
            }

            if(this.menu){
                this.mon(this.menu, {
                    scope: this,
                    show: this.onMenuShow,
                    hide: this.onMenuHide
                });
            }

            if(this.repeat){
                var repeater = new Ext.util.ClickRepeater(btn, Ext.isObject(this.repeat) ? this.repeat : {});
                this.mon(repeater, 'click', this.onRepeatClick, this);
            }else{
                this.mon(btn, this.clickEvent, this.onClick, this);
            }
        },

        // private
        afterRender : function(){
            Ext.Button.superclass.afterRender.call(this);
            this.useSetClass = true;
            this.setButtonClass();
            this.doc = Ext.getDoc();
            this.doAutoWidth();
        },

        /**
         * Sets the CSS class that provides a background image to use as the button's icon.  This method also changes
         * the value of the {@link iconCls} config internally.
         * @param {String} cls The CSS class providing the icon image
         * @return {Ext.Button} this
         */
        setIconClass : function(cls){
            this.iconCls = cls;
            if(this.el){
                this.btnEl.dom.className = '';
                this.btnEl.addClass(['x-btn-text', cls || '']);
                this.setButtonClass();
            }
            return this;
        },

        /**
         * Sets the tooltip for this Button.
         * @param {String/Object} tooltip. This may be:
         * String : A string to be used as innerHTML (html tags are accepted) to show in a tooltip
         * Object : A configuration object for {@link Ext.QuickTips#register}.
         *
         * @return {Ext.Button} this
         */
        setTooltip : function(tooltip, /* private */ initial){
            if(this.rendered){
                if(!initial){
                    this.clearTip();
                }
                if(Ext.isObject(tooltip)){
                    Ext.QuickTips.register(Ext.apply({
                          target: this.btnEl.id
                    }, tooltip));
                    this.tooltip = tooltip;
                }else{
                    this.btnEl.dom[this.tooltipType] = tooltip;
                }
            }else{
                this.tooltip = tooltip;
            }
            return this;
        },

        // private
        clearTip : function(){
            if(Ext.isObject(this.tooltip)){
                Ext.QuickTips.unregister(this.btnEl);
            }
        },

        // private
        beforeDestroy : function(){
            if(this.rendered){
                this.clearTip();
            }
            if(this.menu && this.destroyMenu !== false) {
                Ext.destroy(this.btnEl, this.menu);
            }
            Ext.destroy(this.repeater);
        },

        // private
        onDestroy : function(){
            if(this.rendered){
                this.doc.un('mouseover', this.monitorMouseOver, this);
                this.doc.un('mouseup', this.onMouseUp, this);
                delete this.doc;
                delete this.btnEl;
                Ext.ButtonToggleMgr.unregister(this);
            }
            Ext.Button.superclass.onDestroy.call(this);
        },

        // private
        doAutoWidth : function(){
            if(this.autoWidth !== false && this.el && this.text && this.width === undefined){
                this.el.setWidth('auto');
                if(Ext.isIE7 && Ext.isStrict){
                    var ib = this.btnEl;
                    if(ib && ib.getWidth() > 20){
                        ib.clip();
                        ib.setWidth(Ext.util.TextMetrics.measure(ib, this.text).width+ib.getFrameWidth('lr'));
                    }
                }
                if(this.minWidth){
                    if(this.el.getWidth() < this.minWidth){
                        this.el.setWidth(this.minWidth);
                    }
                }
            }
        },

        /**
         * Assigns this Button's click handler
         * @param {Function} handler The function to call when the button is clicked
         * @param {Object} scope (optional) The scope (this reference) in which the handler function is executed.
         * Defaults to this Button.
         * @return {Ext.Button} this
         */
        setHandler : function(handler, scope){
            this.handler = handler;
            this.scope = scope;
            return this;
        },

        /**
         * Sets this Button's text
         * @param {String} text The button text
         * @return {Ext.Button} this
         */
        setText : function(text){
            this.text = text;
            if(this.el){
                this.btnEl.update(text || ' ');
                this.setButtonClass();
            }
            this.doAutoWidth();
            return this;
        },

        /**
         * Sets the background image (inline style) of the button.  This method also changes
         * the value of the {@link icon} config internally.
         * @param {String} icon The path to an image to display in the button
         * @return {Ext.Button} this
         */
        setIcon : function(icon){
            this.icon = icon;
            if(this.el){
                this.btnEl.setStyle('background-image', icon ? 'url(' + icon + ')' : '');
                this.setButtonClass();
            }
            return this;
        },

        /**
         * Gets the text for this Button
         * @return {String} The button text
         */
        getText : function(){
            return this.text;
        },

        /**
         * If a state it passed, it becomes the pressed state otherwise the current state is toggled.
         * @param {Boolean} state (optional) Force a particular state
         * @param {Boolean} supressEvent (optional) True to stop events being fired when calling this method.
         * @return {Ext.Button} this
         */
        toggle : function(state, suppressEvent){
            state = state === undefined ? !this.pressed : !!state;
            if(state != this.pressed){
                if(this.rendered){
                    this.el[state ? 'addClass' : 'removeClass']('x-btn-pressed');
                }
                this.pressed = state;
                if(!suppressEvent){
                    this.fireEvent('toggle', this, state);
                    if(this.toggleHandler){
                        this.toggleHandler.call(this.scope || this, this, state);
                    }
                }
            }
            return this;
        },

        // private
        onDisable : function(){
            this.onDisableChange(true);
        },

        // private
        onEnable : function(){
            this.onDisableChange(false);
        },

        onDisableChange : function(disabled){
            if(this.el){
                if(!Ext.isIE6 || !this.text){
                    this.el[disabled ? 'addClass' : 'removeClass'](this.disabledClass);
                }
                this.el.dom.disabled = disabled;
            }
            this.disabled = disabled;
        },

        /**
         * Show this button's menu (if it has one)
         */
        showMenu : function(){
            if(this.rendered && this.menu){
                if(this.tooltip){
                    Ext.QuickTips.getQuickTip().cancelShow(this.btnEl);
                }
                if(this.menu.isVisible()){
                    this.menu.hide();
                }
                this.menu.ownerCt = this;
                this.menu.show(this.el, this.menuAlign);
            }
            return this;
        },

        /**
         * Hide this button's menu (if it has one)
         */
        hideMenu : function(){
            if(this.hasVisibleMenu()){
                this.menu.hide();
            }
            return this;
        },

        /**
         * Returns true if the button has a menu and it is visible
         * @return {Boolean}
         */
        hasVisibleMenu : function(){
            return this.menu && this.menu.ownerCt == this && this.menu.isVisible();
        },

        // private
        onRepeatClick : function(repeat, e){
            this.onClick(e);
        },

        // private
        onClick : function(e){
            if(e){
                e.preventDefault();
            }
            if(e.button !== 0){
                return;
            }
            if(!this.disabled){
                this.doToggle();
                if(this.menu && !this.hasVisibleMenu() && !this.ignoreNextClick){
                    this.showMenu();
                }
                this.fireEvent('click', this, e);
                if(this.handler){
                    //this.el.removeClass('x-btn-over');
                    this.handler.call(this.scope || this, this, e);
                }
            }
        },

        // private
        doToggle: function(){
            if (this.enableToggle && (this.allowDepress !== false || !this.pressed)) {
                this.toggle();
            }
        },

        // private
        isMenuTriggerOver : function(e, internal){
            return this.menu && !internal;
        },

        // private
        isMenuTriggerOut : function(e, internal){
            return this.menu && !internal;
        },

        // private
        onMouseOver : function(e){
            if(!this.disabled){
                var internal = e.within(this.el,  true);
                if(!internal){
                    this.el.addClass('x-btn-over');
                    if(!this.monitoringMouseOver){
                        this.doc.on('mouseover', this.monitorMouseOver, this);
                        this.monitoringMouseOver = true;
                    }
                    this.fireEvent('mouseover', this, e);
                }
                if(this.isMenuTriggerOver(e, internal)){
                    this.fireEvent('menutriggerover', this, this.menu, e);
                }
            }
        },

        // private
        monitorMouseOver : function(e){
            if(e.target != this.el.dom && !e.within(this.el)){
                if(this.monitoringMouseOver){
                    this.doc.un('mouseover', this.monitorMouseOver, this);
                    this.monitoringMouseOver = false;
                }
                this.onMouseOut(e);
            }
        },

        // private
        onMouseOut : function(e){
            var internal = e.within(this.el) && e.target != this.el.dom;
            this.el.removeClass('x-btn-over');
            this.fireEvent('mouseout', this, e);
            if(this.isMenuTriggerOut(e, internal)){
                this.fireEvent('menutriggerout', this, this.menu, e);
            }
        },

        focus : function() {
            this.btnEl.focus();
        },

        blur : function() {
            this.btnEl.blur();
        },

        // private
        onFocus : function(e){
            if(!this.disabled){
                this.el.addClass('x-btn-focus');
            }
        },
        // private
        onBlur : function(e){
            this.el.removeClass('x-btn-focus');
        },

        // private
        getClickEl : function(e, isUp){
           return this.el;
        },

        // private
        onMouseDown : function(e){
            if(!this.disabled && e.button === 0){
                this.getClickEl(e).addClass('x-btn-click');
                this.doc.on('mouseup', this.onMouseUp, this);
            }
        },
        // private
        onMouseUp : function(e){
            if(e.button === 0){
                this.getClickEl(e, true).removeClass('x-btn-click');
                this.doc.un('mouseup', this.onMouseUp, this);
            }
        },
        // private
        onMenuShow : function(e){
            if(this.menu.ownerCt == this){
                this.menu.ownerCt = this;
                this.ignoreNextClick = 0;
                this.el.addClass('x-btn-menu-active');
                this.fireEvent('menushow', this, this.menu);
            }
        },
        // private
        onMenuHide : function(e){
            if(this.menu.ownerCt == this){
                this.el.removeClass('x-btn-menu-active');
                this.ignoreNextClick = this.restoreClick.defer(250, this);
                this.fireEvent('menuhide', this, this.menu);
                delete this.menu.ownerCt;
            }
        },

        // private
        restoreClick : function(){
            this.ignoreNextClick = 0;
        }

        /**
         * @cfg {String} autoEl @hide
         */
        /**
         * @cfg {String/Object} html @hide
         */
        /**
         * @cfg {String} contentEl  @hide
         */
        /**
         * @cfg {Mixed} data  @hide
         */
        /**
         * @cfg {Mixed} tpl  @hide
         */
        /**
         * @cfg {String} tplWriteMode  @hide
         */
    });
    Ext.reg('button', Ext.Button);

    // Private utility class used by Button
    Ext.ButtonToggleMgr = function(){
       var groups = {};

       function toggleGroup(btn, state){
           if(state){
               var g = groups[btn.toggleGroup];
               for(var i = 0, l = g.length; i < l; i++){
                   if(g[i] != btn){
                       g[i].toggle(false);
                   }
               }
           }
       }

       return {
           register : function(btn){
               if(!btn.toggleGroup){
                   return;
               }
               var g = groups[btn.toggleGroup];
               if(!g){
                   g = groups[btn.toggleGroup] = [];
               }
               g.push(btn);
               btn.on('toggle', toggleGroup);
           },

           unregister : function(btn){
               if(!btn.toggleGroup){
                   return;
               }
               var g = groups[btn.toggleGroup];
               if(g){
                   g.remove(btn);
                   btn.un('toggle', toggleGroup);
               }
           },

           /**
            * Gets the pressed button in the passed group or null
            * @param {String} group
            * @return Button
            */
           getPressed : function(group){
               var g = groups[group];
               if(g){
                   for(var i = 0, len = g.length; i < len; i++){
                       if(g[i].pressed === true){
                           return g[i];
                       }
                   }
               }
               return null;
           }
       };
    }();