diff --git a/modules/gui/src/data_viewer/data_viewer.cc b/modules/gui/src/data_viewer/data_viewer.cc
index be46724af590ca688681539c721a224974ceaea1..94eb44e683cb9da8c4ab476284345d0d300b6a95 100644
--- a/modules/gui/src/data_viewer/data_viewer.cc
+++ b/modules/gui/src/data_viewer/data_viewer.cc
@@ -64,7 +64,7 @@ int ipow(int base, unsigned int exponent){
 }
 
 DataViewer::DataViewer(QWidget* p, const ImageHandle& data, const QString& name):
-  ost::gui::MainWindow(p,0),
+  ost::gui::MainWindow(p),
   name_(name),
   panel_(new DataViewerPanel(data,this)),
   ov_manager_(new OverlayManager(this)),
diff --git a/modules/gui/src/dock_widget.hh b/modules/gui/src/dock_widget.hh
index 5cebbc73c4a59a74699dda67884345a90c7a0323..9c02a1d0bee096b4655202ac250e42f9f71ce8b2 100644
--- a/modules/gui/src/dock_widget.hh
+++ b/modules/gui/src/dock_widget.hh
@@ -35,7 +35,7 @@ class DLLEXPORT_OST_GUI DockWidget: public QDockWidget
 {
   Q_OBJECT;
 public:
-  DockWidget(const QString& title, QWidget* parent=0, Qt::WindowFlags flags=0);
+  DockWidget(const QString& title, QWidget* parent=0, Qt::WindowFlags flags=Qt::WindowFlags());
   virtual void closeEvent(QCloseEvent* e);
 signals:
   void OnClose(QDockWidget* dock);
diff --git a/modules/gui/src/main_window.hh b/modules/gui/src/main_window.hh
index 56f956000fd9c40222a1b0313a91a77a95c34377..b64e227baa8dd4e458770a9d6d249083ac2c8530 100644
--- a/modules/gui/src/main_window.hh
+++ b/modules/gui/src/main_window.hh
@@ -43,7 +43,7 @@ class DLLEXPORT_OST_GUI MainWindow: public QMainWindow
 
   typedef std::map<QWidget*,QDockWidget*> DockWidgetMap;
 public:
-  MainWindow(QWidget* parent=0, Qt::WindowFlags flags=0);
+  MainWindow(QWidget* parent=0, Qt::WindowFlags flags=Qt::WindowFlags());
 
   //! add a custom docking widget
   void AddDockWidget(QWidget* w, const QString& name, bool show=true, int area=2);
diff --git a/modules/gui/src/python_shell/python_namespace_tree_model.cc b/modules/gui/src/python_shell/python_namespace_tree_model.cc
index 1d3694e5491d2e7f4cce864bf7427d013547f30f..2c56b606fc4edfdb1debbf26e472abac5caa6c3c 100644
--- a/modules/gui/src/python_shell/python_namespace_tree_model.cc
+++ b/modules/gui/src/python_shell/python_namespace_tree_model.cc
@@ -107,11 +107,12 @@ QVariant PythonNamespaceTreeModel::data(const QModelIndex &index, int role) cons
 Qt::ItemFlags PythonNamespaceTreeModel::flags(const QModelIndex &index) const
 {
   if (!index.isValid()){
-    return 0;
+    return Qt::ItemFlags();
   }
   return Qt::ItemIsEnabled | Qt::ItemIsSelectable;
 }
 
+
 QVariant PythonNamespaceTreeModel::headerData(int section, 
                                               Qt::Orientation orientation,
                                               int role) const