new Grayback().show();

grayback.js

p = function() {
	if (typeof console != 'undefined' && typeof console.log == 'function')
		console.log.apply(null, arguments);
};


Grayback = (function() {
	var id = 1;
	var stack = [];
	var memory = null;

	var msie6 = ($.browser.msie && $.browser.version < 7);

	var Grayback = function(css) {
		this.css = $.extend({
			zIndex         : 1000,
			backgroundColor: '#000',
			opacity        : 0.5
		}, css);
		this.uid = id++;
		this.container = null;
		this.forgetSelector = ['iframe', 'select', 'object', 'embed'];
	};
	Grayback.prototype = {
		initialize: function() {
			this.container = $('<div class="grayback"/>');
			var css = $.extend({}, this.css, {
				display: 'none',
				top    : 0,
				left   : 0,
				width  : '100%',
				height : '100%'
			});
			if (msie6) {
				css.position = 'absolute';
				css.height   = Math.max($(window).height(), $().height(), $('body').height());
			}
			else
				css.position = 'fixed';

			this.container
				.css(css)
				.appendTo('body');
		},

		stat: function() {
			if (!p) return;
			p({
				'this': this,
				id    : id,
				stack : stack,
				memory: memory
			});
		},

		show: function() {
			if ($.inArray(this.uid, stack) == -1)
				stack.push(this.uid);

			if (!this.container) {
				this.initialize();
				this.forget();
			}
			this.container.show.apply(this.container, arguments);
		},

		hide: function() {
			var n = $.inArray(this.uid, stack);
			if (n == -1) return;
			stack.splice(n, 1);

			this.container.hide.apply(this.container, arguments);
			this.remember();
		},

		remove: function() {
			var self = this;
			this.container.hide(function() {
				$(this).remove();
				self.container = null;
			});
		},

		forget: function() {
			if (!msie6 || memory) return;

			memory = [];
			$.each(this.forgetSelector, function() {
				$(this).each(function() {
					if ($(this).css('visibility') != 'hidden')
						memory.push(this);
				});
			});
			$(memory).css('visibility', 'hidden');
		},

		remember: function() {
			if (!msie6 || stack.length || !memory) return;
			$(memory).css('visibility', 'visible');
		}
	};

	return Grayback;
})();