Index: /CKEditor/trunk/_source/plugins/panel/plugin.js
===================================================================
--- /CKEditor/trunk/_source/plugins/panel/plugin.js	(revision 3525)
+++ /CKEditor/trunk/_source/plugins/panel/plugin.js	(revision 3526)
@@ -78,4 +78,5 @@
 		output.push(
 			'<div class="', editor.skinClass ,'"' +
+				' lang="', editor.langCode, '"' +
 				' style="z-index:' + ( editor.config.baseFloatZIndex + 1 ) + '">' +
 				'<div' +
@@ -131,4 +132,5 @@
 					dir = parentDiv.getAttribute( 'dir' ),
 					className = parentDiv.getParent().getAttribute( 'class' ),
+					langCode = parentDiv.getParent().getAttribute( 'lang' ),
 					doc = iframe.getFrameDocument();
 
@@ -142,5 +144,5 @@
 				doc.$.write(
 					'<!DOCTYPE html>' +
-					'<html dir="' + dir + '" class="' + className + '_container">' +
+					'<html dir="' + dir + '" class="' + className + '_container" lang="' + langCode + '">' +
 						'<head>' +
 							'<style>.' + className + '_container{visibility:hidden}</style>' +
Index: /CKEditor/trunk/_source/themes/default/theme.js
===================================================================
--- /CKEditor/trunk/_source/themes/default/theme.js	(revision 3525)
+++ /CKEditor/trunk/_source/themes/default/theme.js	(revision 3526)
@@ -54,4 +54,5 @@
 					' dir="', editor.lang.dir, '"' +
 					' title="', ( CKEDITOR.env.gecko ? ' ' : '' ), '"' +
+					' lang="', editor.langCode, '"' +
 					' tabindex="' + tabIndex + '">' +
 				'<span class="' , CKEDITOR.env.cssClass, ' cke_', editor.lang.dir, '">' +
@@ -94,5 +95,7 @@
 			var element = CKEDITOR.dom.element.createFromHtml( [
 					'<div class="cke_skin_', editor.skinName,
-						'" dir="', editor.lang.dir, '">' +
+						'" dir="', editor.lang.dir, '"' +
+						' lang="', editor.langCode, '"' +
+						'>' +
 
 						'<div class="cke_dialog', ' ' + CKEDITOR.env.cssClass,
