add include directory
diff --git a/demo/chatdialog.ui b/demo/chatdialog.ui
index 072d139..b7a6747 100644
--- a/demo/chatdialog.ui
+++ b/demo/chatdialog.ui
@@ -25,7 +25,7 @@
             <number>6</number>
           </property>
           <item>
-            <widget class="DigestTreeViewer" name="treeViewer">
+            <widget class="QGraphicsView" name="treeViewer">
             <property name="focusPolicy">
               <enum>Qt::NoFocus</enum>
             </property>