Ticket #23817: 23817.patch

wp-admin/js/common.js

@@ -169 +169 @@
         });
 
         $('#collapse-menu').on('click.collapse-menu', function(e){
-                var body = $(document.body);
+                var body = $( document.body ), respWidth;
 
                 // reset any compensation for submenus near the bottom of the screen
                 $('#adminmenu div.wp-submenu').css('margin-top', '');
 
-                if ( $(window).width() < 900 ) {
+                // WebKit excludes the width of the vertical scrollbar when applying the CSS "@media screen and (max-width: 900px)"
+                // and matches $(window).width().
+                // Firefox and IE > 8 include the scrollbar width, so after the jQuery normalization
+                // $(window).width() is 884px but window.innerWidth is 900px.
+                // (using window.innerWidth also excludes IE < 9)
+                respWidth = navigator.userAgent.indexOf('AppleWebKit/') > -1 ? $(window).width() : window.innerWidth;
+
+                if ( respWidth && respWidth < 900 ) {
                         if ( body.hasClass('auto-fold') ) {
-                                body.removeClass('auto-fold');
+                                body.removeClass('auto-fold').removeClass('folded');
                                 setUserSetting('unfold', 1);
-                                body.removeClass('folded');
                                 deleteUserSetting('mfold');
                         } else {
                                 body.addClass('auto-fold');