diff --git a/sierra-tools/previewer/src/main/java/org/httprpc/sierra/tools/previewer/MainFrame.java b/sierra-tools/previewer/src/main/java/org/httprpc/sierra/tools/previewer/MainFrame.java
index 700b894..b5dac78 100644
--- a/sierra-tools/previewer/src/main/java/org/httprpc/sierra/tools/previewer/MainFrame.java
+++ b/sierra-tools/previewer/src/main/java/org/httprpc/sierra/tools/previewer/MainFrame.java
@@ -20,6 +20,7 @@
 import org.fife.ui.autocomplete.AutoCompletion;
 import org.fife.ui.autocomplete.CompletionProvider;
 import org.fife.ui.rsyntaxtextarea.RSyntaxTextArea;
+import org.fife.ui.rtextarea.RTextScrollPane;
 import org.fife.ui.rsyntaxtextarea.SyntaxConstants;
 import org.fife.ui.rtextarea.SearchEngine;
 import org.fife.ui.rtextarea.SearchResult;
@@ -38,7 +39,6 @@
 import javax.swing.JMenuItem;
 import javax.swing.JOptionPane;
 import javax.swing.JPanel;
-import javax.swing.JScrollPane;
 import javax.swing.JSplitPane;
 import javax.swing.KeyStroke;
 import javax.swing.SwingWorker;
@@ -85,19 +85,21 @@ public class MainFrame extends JFrame implements SearchListener {
     private @Outlet JMenuItem exitItem = null;
     private @Outlet JMenuItem aboutItem = null;
     private @Outlet JSplitPane splitPane = null;
-    private @Outlet JScrollPane editorScrollPane = null;
     private @Outlet JPanel previewPanel = null;
     private @Outlet JLabel statusBar = null;
-    private @Outlet JLabel filePathLabel = null; // The <label> for the file path
+    private @Outlet JLabel filePathLabel = null;
+
 
     // --- Manually Created Components ---
     private FindDialog findDialog = null;
     private ReplaceDialog replaceDialog = null;
     private RSyntaxTextArea editorPane = null;
+    private RTextScrollPane editorScrollPane = null;
+
 
     public MainFrame() {
         super("Sierra UI Previewer");
-
+        
         renderingEngine = new RenderingEngine();
         recentFilesManager = new RecentFilesManager(MainFrame.class);
 
@@ -245,7 +247,6 @@ private void setupCustomEditor() {
         editorPane.setSyntaxEditingStyle(SyntaxConstants.SYNTAX_STYLE_XML);
         editorPane.setCodeFoldingEnabled(true);
         editorPane.setAntiAliasingEnabled(true);
-        editorPane.setEditable(true); // Ensure it's editable
 
         var provider = createCompletionProvider();
 
@@ -258,8 +259,11 @@ private void setupCustomEditor() {
         if (provider != null) {
             ac.install(editorPane);
         }
+        editorScrollPane = new RTextScrollPane(editorPane);
+        editorScrollPane.setLineNumbersEnabled(true);
+        editorScrollPane.setFoldIndicatorEnabled(true);
+        splitPane.setLeftComponent(editorScrollPane);
 
-        editorScrollPane.setViewportView(editorPane);
     }
 
     // -- Extra search/replace functionality
diff --git a/sierra-tools/previewer/src/main/resources/org/httprpc/sierra/tools/previewer/MainFrame.xml b/sierra-tools/previewer/src/main/resources/org/httprpc/sierra/tools/previewer/MainFrame.xml
index 4415b81..1c375fa 100644
--- a/sierra-tools/previewer/src/main/resources/org/httprpc/sierra/tools/previewer/MainFrame.xml
+++ b/sierra-tools/previewer/src/main/resources/org/httprpc/sierra/tools/previewer/MainFrame.xml
@@ -22,7 +22,7 @@
     </menu-bar>
 
     <split-pane name="splitPane" resizeWeight="0.5" weight="1">
-        <scroll-pane name="editorScrollPane" weight="1"/>
+        <label text="Code editor will replace this at runtime"/>
         <column-panel name="previewPanel" padding="5, 5, 5, 5" weight="1"/>
     </split-pane>