Index: wp-admin/js/common.js
===================================================================
--- wp-admin/js/common.js	(revision 21756)
+++ wp-admin/js/common.js	(working copy)
@@ -187,6 +187,7 @@
 		} else {
 			if ( body.hasClass('folded') ) {
 				body.removeClass('folded');
+				setUserSetting('unfold', 1);
 				deleteUserSetting('mfold');
 			} else {
 				body.addClass('folded');