Index: src/wp-includes/js/admin-bar.js
===================================================================
--- src/wp-includes/js/admin-bar.js	(revision 26300)
+++ src/wp-includes/js/admin-bar.js	(working copy)
@@ -22,7 +22,7 @@
 
 				if ( !el.hasClass('hover') ) {
 					e.preventDefault();
-					adminbar.find('li.menupop.hover').removeClass('hover');
+					adminbar.find('li.menupop.hover').not( el.parents('.menupop') ).removeClass('hover');
 					el.addClass('hover');
 				}