diff --git a/demo-edit-jvm/src/main/java/org/sudu/experiments/TMain.java b/demo-edit-jvm/src/main/java/org/sudu/experiments/TMain.java
index 4cfd9f24f..8a0edb470 100644
--- a/demo-edit-jvm/src/main/java/org/sudu/experiments/TMain.java
+++ b/demo-edit-jvm/src/main/java/org/sudu/experiments/TMain.java
@@ -1,6 +1,7 @@
 package org.sudu.experiments;
 
 import org.sudu.experiments.diff.FileDiff;
+import org.sudu.experiments.diff.FolderDiffScene;
 import org.sudu.experiments.diff.UiToolsDemo;
 import org.sudu.experiments.editor.Editor1;
 import org.sudu.experiments.editor.SelectFileTest;
@@ -40,6 +41,10 @@ interface FileDiffMain {
     static void main(String[] $) { run(FileDiff::new); }
   }
 
+  interface FolderDiffMain {
+    static void main(String[] $) { run(FolderDiffScene::new); }
+  }
+
   interface WindowsDemoMain {
     static void main(String[] $) { run(WindowsDemo::new); }
   }
diff --git a/demo-edit/src/main/java/org/sudu/experiments/diff/FolderDiffWindow.java b/demo-edit/src/main/java/org/sudu/experiments/diff/FolderDiffWindow.java
index 558799f22..a6a4b9c42 100644
--- a/demo-edit/src/main/java/org/sudu/experiments/diff/FolderDiffWindow.java
+++ b/demo-edit/src/main/java/org/sudu/experiments/diff/FolderDiffWindow.java
@@ -27,7 +27,7 @@
 public class FolderDiffWindow extends ToolWindow0 {
 
   private static final boolean PRINT_STAT = true;
-  private static final boolean dummyMergeButtons = true;
+  private static final boolean dummyMergeButtons = false;
 
   Window window;
   Focusable focusSave;
@@ -263,10 +263,12 @@ private void updateModel() {
         rootView.left.model(),
         rootView.right.model()
     ));
-    rootView.setMergeButtons(null);
-    if (dummyMergeButtons) {
-      dummyMergeButtons(rootView.left, true);
-      dummyMergeButtons(rootView.right, false);
+    if (leftRoot != null && rightRoot != null) {
+      rootView.setMergeButtons(null);
+      if (dummyMergeButtons) {
+        dummyMergeButtons(rootView.left, true);
+        dummyMergeButtons(rootView.right, false);
+      }
     }
   }
 
diff --git a/demo-edit/src/main/java/org/sudu/experiments/ui/FileTreeNode.java b/demo-edit/src/main/java/org/sudu/experiments/ui/FileTreeNode.java
index 45daf6d4f..a7ae95b70 100644
--- a/demo-edit/src/main/java/org/sudu/experiments/ui/FileTreeNode.java
+++ b/demo-edit/src/main/java/org/sudu/experiments/ui/FileTreeNode.java
@@ -95,7 +95,7 @@ private int getModel(TreeNode[] t, FolderDiffModel[] m, FolderDiffModel model, F
     if (isOpened()) {
       if (model.children == null) {
         for (FileTreeNode child: children)
-          idx = child.getModel(t, diffType, idx, model.isCompared());
+          idx = child.getModel(t, m, diffType, idx, model.isCompared());
       } else {
         int i = 0, j = 0;
         for (FolderDiffModel child: model.children) {
@@ -117,13 +117,14 @@ private int getModel(TreeNode[] t, FolderDiffModel[] m, FolderDiffModel model, F
     return idx;
   }
 
-  private int getModel(TreeNode[] t, int diffType, int idx, boolean compared) {
+  private int getModel(TreeNode[] t, FolderDiffModel[] m, int diffType, int idx, boolean compared) {
     this.diffType = diffType;
-    t[idx++] = this;
+    t[idx] = this;
+    m[idx++] = new FolderDiffModel(null);
     setIcon(this, compared);
     if (isOpened()) {
       for (var child: children)
-        idx = child.getModel(t, diffType, idx, compared);
+        idx = child.getModel(t, m, diffType, idx, compared);
     }
     return idx;
   }