draws tree
diff --git a/demo/digesttreeviewer.cpp b/demo/digesttreeviewer.cpp
new file mode 100644
index 0000000..cb52a9e
--- /dev/null
+++ b/demo/digesttreeviewer.cpp
@@ -0,0 +1,10 @@
+#include "digesttreeviewer.h"
+#include "digesttreescene.h"
+#include <QtGui>
+
+DigestTreeViewer::DigestTreeViewer(QWidget *parent)
+  : QGraphicsView(parent) 
+{
+  DigestTreeScene *scene = new DigestTreeScene(this);
+  setScene(scene);
+}