Index: nav-menu.js
===================================================================
--- nav-menu.js	(revision 42022)
+++ nav-menu.js	(working copy)
@@ -829,6 +829,17 @@
 					}
 				}
 			});
+			$('#menu-name').keyup(function(e){
+				menuName = $('#menu-name'),
+				menuNameVal = menuName.val();
+				if( !menuNameVal || menuNameVal == menuName.attr('title') || !menuNameVal.replace(/\s+/, '') ) {
+					// Add warning for invalid menu name
+					menuName.parent().addClass('form-invalid');
+				} else {
+					// Remove warning for valid menu name
+					menuName.parent().removeClass('form-invalid');
+				}
+			});
 			$('#add-custom-links input[type="text"]').keypress(function(e){
 				$('#customlinkdiv').removeClass('form-invalid');