diff --git a/src/voutline.cpp b/src/voutline.cpp
index efda9a44..c40d5897 100644
--- a/src/voutline.cpp
+++ b/src/voutline.cpp
@@ -11,14 +11,13 @@
 extern VNote *g_vnote;
 
 VOutline::VOutline(QWidget *parent)
-    : QTreeWidget(parent),
+    : VTreeWidget(parent),
       VNavigationMode(),
       m_muted(false)
 {
     setColumnCount(1);
     setHeaderHidden(true);
     setSelectionMode(QAbstractItemView::SingleSelection);
-    setAttribute(Qt::WA_MacShowFocusRect, false);
 
     // TODO: jump to the header when user click the same item twice.
     connect(this, &VOutline::currentItemChanged,
@@ -219,7 +218,7 @@ void VOutline::keyPressEvent(QKeyEvent *event)
         break;
     }
 
-    QTreeWidget::keyPressEvent(event);
+    VTreeWidget::keyPressEvent(event);
 }
 
 void VOutline::showNavigation()
diff --git a/src/voutline.h b/src/voutline.h
index 3f21afd2..78680cc9 100644
--- a/src/voutline.h
+++ b/src/voutline.h
@@ -1,10 +1,11 @@
 #ifndef VOUTLINE_H
 #define VOUTLINE_H
 
-#include <QTreeWidget>
 #include <QVector>
 #include <QMap>
 #include <QChar>
+
+#include "vtreewidget.h"
 #include "vtableofcontent.h"
 #include "vnavigationmode.h"
 
@@ -12,7 +13,7 @@ class QLabel;
 
 // Display table of content as a tree and enable user to click an item to
 // jump to that header.
-class VOutline : public QTreeWidget, public VNavigationMode
+class VOutline : public VTreeWidget, public VNavigationMode
 {
     Q_OBJECT
 public:
diff --git a/src/vtreewidget.cpp b/src/vtreewidget.cpp
index 3bb536dd..d9af30e1 100644
--- a/src/vtreewidget.cpp
+++ b/src/vtreewidget.cpp
@@ -5,7 +5,6 @@
 #include <QCoreApplication>
 #include <QSet>
 #include <QScrollBar>
-#include <QDebug>
 #include <QGraphicsOpacityEffect>
 #include <QTimer>