The source code

    /*!
     * Ext JS Library 3.2.1
     * Copyright(c) 2006-2010 Ext JS, Inc.
     * licensing@extjs.com
     * http://www.extjs.com/license
     */
    /**
     * @class Ext.KeyMap
     * Handles mapping keys to actions for an element. One key map can be used for multiple actions.
     * The constructor accepts the same config object as defined by {@link #addBinding}.
     * If you bind a callback function to a KeyMap, anytime the KeyMap handles an expected key
     * combination it will call the function with this signature (if the match is a multi-key
     * combination the callback will still be called only once): (String key, Ext.EventObject e)
     * A KeyMap can also handle a string representation of keys.

     * Usage:

    // map one key by key code
    var map = new Ext.KeyMap("my-element", {
        key: 13, // or Ext.EventObject.ENTER
        fn: myHandler,
        scope: myObject
    });

    // map multiple keys to one action by string
    var map = new Ext.KeyMap("my-element", {
        key: "a\r\n\t",
        fn: myHandler,
        scope: myObject
    });

    // map multiple keys to multiple actions by strings and array of codes
    var map = new Ext.KeyMap("my-element", [
        {
            key: [10,13],
            fn: function(){ alert("Return was pressed"); }
        }, {
            key: "abc",
            fn: function(){ alert('a, b or c was pressed'); }
        }, {
            key: "\t",
            ctrl:true,
            shift:true,
            fn: function(){ alert('Control + shift + tab was pressed.'); }
        }
    ]);

     * Note: A KeyMap starts enabled
     * @constructor
     * @param {Mixed} el The element to bind to
     * @param {Object} config The config (see {@link #addBinding})
     * @param {String} eventName (optional) The event to bind to (defaults to "keydown")
     */
    Ext.KeyMap = function(el, config, eventName){
        this.el  = Ext.get(el);
        this.eventName = eventName || "keydown";
        this.bindings = [];
        if(config){
            this.addBinding(config);
        }
        this.enable();
    };

    Ext.KeyMap.prototype = {
        /**
         * True to stop the event from bubbling and prevent the default browser action if the
         * key was handled by the KeyMap (defaults to false)
         * @type Boolean
         */
        stopEvent : false,

        /**
         * Add a new binding to this KeyMap. The following config object properties are supported:
         *
    Property    Type             Description
    ----------  ---------------  ----------------------------------------------------------------------
    key         String/Array     A single keycode or an array of keycodes to handle
    shift       Boolean          True to handle key only when shift is pressed, False to handle the key only when shift is not pressed (defaults to undefined)
    ctrl        Boolean          True to handle key only when ctrl is pressed, False to handle the key only when ctrl is not pressed (defaults to undefined)
    alt         Boolean          True to handle key only when alt is pressed, False to handle the key only when alt is not pressed (defaults to undefined)
    handler     Function         The function to call when KeyMap finds the expected key combination
    fn          Function         Alias of handler (for backwards-compatibility)
    scope       Object           The scope of the callback function
    stopEvent   Boolean          True to stop the event from bubbling and prevent the default browser action if the key was handled by the KeyMap (defaults to false)

         *
         * Usage:
         *
    // Create a KeyMap
    var map = new Ext.KeyMap(document, {
        key: Ext.EventObject.ENTER,
        fn: handleKey,
        scope: this
    });

    //Add a new binding to the existing KeyMap later
    map.addBinding({
        key: 'abc',
        shift: true,
        fn: handleKey,
        scope: this
    });

         * @param {Object/Array} config A single KeyMap config or an array of configs
         */
    	addBinding : function(config){
            if(Ext.isArray(config)){
                Ext.each(config, function(c){
                    this.addBinding(c);
                }, this);
                return;
            }
            var keyCode = config.key,
                fn = config.fn || config.handler,
                scope = config.scope;

    	if (config.stopEvent) {
    	    this.stopEvent = config.stopEvent;
    	}

            if(typeof keyCode == "string"){
                var ks = [];
                var keyString = keyCode.toUpperCase();
                for(var j = 0, len = keyString.length; j < len; j++){
                    ks.push(keyString.charCodeAt(j));
                }
                keyCode = ks;
            }
            var keyArray = Ext.isArray(keyCode);

            var handler = function(e){
                if(this.checkModifiers(config, e)){
                    var k = e.getKey();
                    if(keyArray){
                        for(var i = 0, len = keyCode.length; i < len; i++){
                            if(keyCode[i] == k){
                              if(this.stopEvent){
                                  e.stopEvent();
                              }
                              fn.call(scope || window, k, e);
                              return;
                            }
                        }
                    }else{
                        if(k == keyCode){
                            if(this.stopEvent){
                               e.stopEvent();
                            }
                            fn.call(scope || window, k, e);
                        }
                    }
                }
            };
            this.bindings.push(handler);
    	},

        // private
        checkModifiers: function(config, e){
            var val, key, keys = ['shift', 'ctrl', 'alt'];
            for (var i = 0, len = keys.length; i < len; ++i){
                key = keys[i];
                val = config[key];
                if(!(val === undefined || (val === e[key + 'Key']))){
                    return false;
                }
            }
            return true;
        },

        /**
         * Shorthand for adding a single key listener
         * @param {Number/Array/Object} key Either the numeric key code, array of key codes or an object with the
         * following options:
         * {key: (number or array), shift: (true/false), ctrl: (true/false), alt: (true/false)}
         * @param {Function} fn The function to call
         * @param {Object} scope (optional) The scope (this reference) in which the function is executed. Defaults to the browser window.
         */
        on : function(key, fn, scope){
            var keyCode, shift, ctrl, alt;
            if(typeof key == "object" && !Ext.isArray(key)){
                keyCode = key.key;
                shift = key.shift;
                ctrl = key.ctrl;
                alt = key.alt;
            }else{
                keyCode = key;
            }
            this.addBinding({
                key: keyCode,
                shift: shift,
                ctrl: ctrl,
                alt: alt,
                fn: fn,
                scope: scope
            });
        },

        // private
        handleKeyDown : function(e){
    	    if(this.enabled){ //just in case
        	    var b = this.bindings;
        	    for(var i = 0, len = b.length; i < len; i++){
        	        b[i].call(this, e);
        	    }
    	    }
    	},

    	/**
    	 * Returns true if this KeyMap is enabled
    	 * @return {Boolean}
    	 */
    	isEnabled : function(){
    	    return this.enabled;
    	},

    	/**
    	 * Enables this KeyMap
    	 */
    	enable: function(){
    		if(!this.enabled){
    		    this.el.on(this.eventName, this.handleKeyDown, this);
    		    this.enabled = true;
    		}
    	},

    	/**
    	 * Disable this KeyMap
    	 */
    	disable: function(){
    		if(this.enabled){
    		    this.el.removeListener(this.eventName, this.handleKeyDown, this);
    		    this.enabled = false;
    		}
    	},

        /**
         * Convenience function for setting disabled/enabled by boolean.
         * @param {Boolean} disabled
         */
        setDisabled : function(disabled){
            this[disabled ? "disable" : "enable"]();
        }
    };