    /**
     * @class Ext.util.DelayedTask
     *
     * The DelayedTask class provides a convenient way to "buffer" the execution of a method,
     * performing setTimeout where a new timeout cancels the old timeout. When called, the
     * task will wait the specified time period before executing. If durng that time period,
     * the task is called again, the original call will be cancelled. This continues so that
     * the function is only called a single time for each iteration.
     *
     * This method is especially useful for things like detecting whether a user has finished
     * typing in a text field. An example would be performing validation on a keypress. You can
     * use this class to buffer the keypress events for a certain number of milliseconds, and
     * perform only if they stop for that amount of time.
     *
     * ## Usage
     *
     *     var task = new Ext.util.DelayedTask(function(){
     *         alert(Ext.getDom('myInputField').value.length);
     *     });
     *
     *     // Wait 500ms before calling our function. If the user presses another key
     *     // during that 500ms, it will be cancelled and we'll wait another 500ms.
     *     Ext.get('myInputField').on('keypress', function(){
     *         task.{@link #delay}(500);
     *     });
     *
     * Note that we are using a DelayedTask here to illustrate a point. The configuration
     * option `buffer` for {@link Ext.util.Observable#addListener addListener/on} will
     * also setup a delayed task for you to buffer events.
     *
     * @constructor The parameters to this constructor serve as defaults and are not required.
     * @param {Function} fn (optional) The default function to call.
     * @param {Object} scope The default scope (The <code><b>this</b></code> reference) in which the
     * function is called. If not specified, <code>this</code> will refer to the browser window.
     * @param {Array} args (optional) The default Array of arguments.
     */
    Ext.util.DelayedTask = function(fn, scope, args) {
        var me = this,
            id,
            call = function() {
                clearInterval(id);
                id = null;
                fn.apply(scope, args || []);
            };

        /**
         * Cancels any pending timeout and queues a new one
         * @param {Number} delay The milliseconds to delay
         * @param {Function} newFn (optional) Overrides function passed to constructor
         * @param {Object} newScope (optional) Overrides scope passed to constructor. Remember that if no scope
         * is specified, <code>this</code> will refer to the browser window.
         * @param {Array} newArgs (optional) Overrides args passed to constructor
         */
        this.delay = function(delay, newFn, newScope, newArgs) {
            me.cancel();
            fn = newFn || fn;
            scope = newScope || scope;
            args = newArgs || args;
            id = setInterval(call, delay);
        };

        /**
         * Cancel the last queued timeout
         */
        this.cancel = function(){
            if (id) {
                clearInterval(id);
                id = null;
            }
        };
    };