diff --git a/src/ace/Document.js b/src/ace/Document.js
index 4c359879..2bb17c99 100644
--- a/src/ace/Document.js
+++ b/src/ace/Document.js
@@ -116,7 +116,7 @@ var Document = function(text, mode) {
 
     this.$tabSize = 4;
     this.setTabSize = function(tabSize) {
-        if (this.$tabSize === tabSize) return;
+        if (isNaN(tabSize) || this.$tabSize === tabSize) return;
 
         this.modified = true;
         this.$tabSize = tabSize;
diff --git a/src/ace/Editor.js b/src/ace/Editor.js
index ba61e99c..5cd621d1 100644
--- a/src/ace/Editor.js
+++ b/src/ace/Editor.js
@@ -482,7 +482,7 @@ var Editor = function(renderer, doc) {
     };
 
     this.getReadOnly = function() {
-        return this.readOnly;
+        return this.$readOnly;
     };
 
     this.removeRight = function() {
diff --git a/src/ace/VirtualRenderer.js b/src/ace/VirtualRenderer.js
index 7da25171..a8d48814 100644
--- a/src/ace/VirtualRenderer.js
+++ b/src/ace/VirtualRenderer.js
@@ -57,6 +57,8 @@ var VirtualRenderer = function(container) {
         column : 0
     };
 
+    this.showInvisibles = false;
+
     this.$drawCallbacks = [];
 
     this.$updatePrintMargin();
diff --git a/src/ace/layer/Text.js b/src/ace/layer/Text.js
index efe121ac..d2ed83f4 100644
--- a/src/ace/layer/Text.js
+++ b/src/ace/layer/Text.js
@@ -123,7 +123,7 @@ var Text = function(parentEl) {
 
             var lineElement = lineElements[i - layerConfig.firstRow];
             lineElement.innerHTML = html.join("");
-        };
+        }
     };
 
     this.$scrollLines = function(oldConfig, config) {