diff --git a/lib/ace/config.js b/lib/ace/config.js
index 4a7dc286..97a18954 100644
--- a/lib/ace/config.js
+++ b/lib/ace/config.js
@@ -93,22 +93,37 @@ exports.setModuleUrl = function(name, subst) {
     return options.$moduleUrls[name] = subst;
 };
 
+exports.$loading = {};
 exports.loadModule = function(moduleName, onLoad) {
     var module, moduleType;
     if (Array.isArray(moduleName)) {
         moduleType = moduleName[0];
         moduleName = moduleName[1];
     }
+
     try {
         module = require(moduleName);
     } catch (e) {};
-    if (module)
+    // require(moduleName) can return empty object if called after require([moduleName], callback)
+    if (module && !exports.$loading[moduleName])
         return onLoad && onLoad(module);
 
+    if (!exports.$loading[moduleName])
+        exports.$loading[moduleName] = [];
+
+    exports.$loading[moduleName].push(onLoad);
+
+    if (exports.$loading[moduleName].length > 1)
+        return;
+
     var afterLoad = function() {
         require([moduleName], function(module) {
             exports._emit("load.module", {name: moduleName, module: module});
-            onLoad && onLoad(module);
+            var listeners = exports.$loading[moduleName];
+            exports.$loading[moduleName] = null;
+            listeners.forEach(function(onLoad) {
+                onLoad && onLoad(module);
+            });
         });
     };
 
diff --git a/lib/ace/virtual_renderer.js b/lib/ace/virtual_renderer.js
index 7ef2f106..a76ec222 100644
--- a/lib/ace/virtual_renderer.js
+++ b/lib/ace/virtual_renderer.js
@@ -496,7 +496,7 @@ var VirtualRenderer = function(container, theme) {
         var style = this.$printMarginEl.style;
         style.left = ((this.characterWidth * this.$printMarginColumn) + this.$padding) + "px";
         style.visibility = this.$showPrintMargin ? "visible" : "hidden";
-
+        
         if (this.session && this.session.$wrap == -1)
             this.adjustWrapLimit();
     };
@@ -1268,6 +1268,8 @@ var VirtualRenderer = function(container, theme) {
         }
 
         function afterLoad(theme) {
+            if (!theme.cssClass)
+                return;
             dom.importCssString(
                 theme.cssText,
                 theme.cssClass,
@@ -1367,7 +1369,7 @@ config.defineOptions(VirtualRenderer.prototype, "renderer", {
             this.$updatePrintMargin();
         },
         get: function() {
-            return this.$showPrintMargin && this.$printMarginColumn;
+            return this.$showPrintMargin && this.$printMarginColumn; 
         }
     },
     showGutter: {