diff -r 2f6f6f7551ca -r 32102edaa81b web/wp-includes/js/customize-preview.dev.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/web/wp-includes/js/customize-preview.dev.js	Mon Nov 19 18:26:13 2012 +0100
@@ -0,0 +1,146 @@
+(function( exports, $ ){
+	var api = wp.customize,
+		debounce;
+
+	debounce = function( fn, delay, context ) {
+		var timeout;
+		return function() {
+			var args = arguments;
+
+			context = context || this;
+
+			clearTimeout( timeout );
+			timeout = setTimeout( function() {
+				timeout = null;
+				fn.apply( context, args );
+			}, delay );
+		};
+	};
+
+	api.Preview = api.Messenger.extend({
+		/**
+		 * Requires params:
+		 *  - url    - the URL of preview frame
+		 */
+		initialize: function( params, options ) {
+			var self = this;
+
+			api.Messenger.prototype.initialize.call( this, params, options );
+
+			this.body = $( document.body );
+			this.body.on( 'click.preview', 'a', function( event ) {
+				event.preventDefault();
+				self.send( 'scroll', 0 );
+				self.send( 'url', $(this).prop('href') );
+			});
+
+			// You cannot submit forms.
+			// @todo: Allow form submissions by mixing $_POST data with the customize setting $_POST data.
+			this.body.on( 'submit.preview', 'form', function( event ) {
+				event.preventDefault();
+			});
+
+			this.window = $( window );
+			this.window.on( 'scroll.preview', debounce( function() {
+				self.send( 'scroll', self.window.scrollTop() );
+			}, 200 ));
+
+			this.bind( 'scroll', function( distance ) {
+				self.window.scrollTop( distance );
+			});
+		}
+	});
+
+	$( function() {
+		api.settings = window._wpCustomizeSettings;
+		if ( ! api.settings )
+			return;
+
+		var preview, bg;
+
+		preview = new api.Preview({
+			url: window.location.href,
+			channel: api.settings.channel
+		});
+
+		preview.bind( 'settings', function( values ) {
+			$.each( values, function( id, value ) {
+				if ( api.has( id ) )
+					api( id ).set( value );
+				else
+					api.create( id, value );
+			});
+		});
+
+		preview.trigger( 'settings', api.settings.values );
+
+		preview.bind( 'setting', function( args ) {
+			var value;
+
+			args = args.slice();
+
+			if ( value = api( args.shift() ) )
+				value.set.apply( value, args );
+		});
+
+		preview.bind( 'sync', function( events ) {
+			$.each( events, function( event, args ) {
+				preview.trigger( event, args );
+			});
+			preview.send( 'synced' );
+		});
+
+	 	preview.bind( 'active', function() {
+	 		if ( api.settings.nonce )
+	 			preview.send( 'nonce', api.settings.nonce );
+	 	});
+
+		preview.send( 'ready' );
+
+		/* Custom Backgrounds */
+		bg = $.map(['color', 'image', 'position_x', 'repeat', 'attachment'], function( prop ) {
+			return 'background_' + prop;
+		});
+
+		api.when.apply( api, bg ).done( function( color, image, position_x, repeat, attachment ) {
+			var body = $(document.body),
+				head = $('head'),
+				style = $('#custom-background-css'),
+				update;
+
+			// If custom backgrounds are active and we can't find the
+			// default output, bail.
+			if ( body.hasClass('custom-background') && ! style.length )
+				return;
+
+			update = function() {
+				var css = '';
+
+				// The body will support custom backgrounds if either
+				// the color or image are set.
+				//
+				// See get_body_class() in /wp-includes/post-template.php
+				body.toggleClass( 'custom-background', !! ( color() || image() ) );
+
+				if ( color() )
+					css += 'background-color: ' + color() + ';';
+
+				if ( image() ) {
+					css += 'background-image: url("' + image() + '");';
+					css += 'background-position: top ' + position_x() + ';';
+					css += 'background-repeat: ' + repeat() + ';';
+					css += 'background-position: top ' + attachment() + ';';
+				}
+
+				// Refresh the stylesheet by removing and recreating it.
+				style.remove();
+				style = $('<style type="text/css" id="custom-background-css">body.custom-background { ' + css + ' }</style>').appendTo( head );
+			};
+
+			$.each( arguments, function() {
+				this.bind( update );
+			});
+		});
+	});
+
+})( wp, jQuery );