Prevent 'Enter menu name here' menus, and offer some feedback. props koopersmith, fixes #13703.

git-svn-id: https://develop.svn.wordpress.org/trunk@15124 602fd350-edb4-49c9-b593-d223f7449a82

wp-admin/css/nav-menu.dev.css

@@ -529,6 +529,14 @@ body.js .item-order {
 	color: #fff;
 }
 
+.major-publishing-actions .form-invalid {
+	border-radius: 4px;
+	-webkit-border-radius: 4px;
+	-moz-border-radius: 4px;
+	-khtml-border-radius: 4px;
+	padding-left: 4px;
+	margin-left: -4px;
+}
 
 /* Clearfix */
 #menu-item-name-wrap:after,

wp-admin/js/nav-menu.dev.js

@@ -806,7 +806,14 @@ var wpNavMenu;
 		},
 
 		eventOnClickMenuSave : function(clickedEl) {
-			var locs = '';
+			var locs = '',
+			menuName = $('#menu-name'),
+			menuNameVal = menuName.val();
+			// Cancel and warn if invalid menu name
+			if( !menuNameVal || menuNameVal == menuName.attr('title') || !menuNameVal.replace(/\s+/, '') ) {
+				menuName.parent().addClass('form-invalid');
+				return false;
+			}
 			// Copy menu theme locations
 			$('#nav-menu-theme-locations select').each(function() {
 				locs += '<input type="hidden" name="' + this.name + '" value="' + $(this).val() + '" />';