diff --git a/Modules/QtWidgets/include/QmitkInteractionSchemeToolBar.h b/Modules/QtWidgets/include/QmitkInteractionSchemeToolBar.h
index 49f1c58eec..d230c84a77 100644
--- a/Modules/QtWidgets/include/QmitkInteractionSchemeToolBar.h
+++ b/Modules/QtWidgets/include/QmitkInteractionSchemeToolBar.h
@@ -1,56 +1,56 @@
 /*============================================================================
 
 The Medical Imaging Interaction Toolkit (MITK)
 
 Copyright (c) German Cancer Research Center (DKFZ)
 All rights reserved.
 
 Use of this source code is governed by a 3-clause BSD license that can be
 found in the LICENSE file.
 
 ============================================================================*/
 
 #ifndef QMITKINTERACTIONSCHEMETOOLBAR_H
 #define QMITKINTERACTIONSCHEMETOOLBAR_H
 
 #include "MitkQtWidgetsExports.h"
 
 // mitk core
 #include "mitkInteractionSchemeSwitcher.h"
 
 #include <QActionGroup>
 #include <QToolBar>
 
 /**
 * @brief
 *
 *
 */
 class MITKQTWIDGETS_EXPORT QmitkInteractionSchemeToolBar : public QToolBar
 {
   Q_OBJECT
 
 public:
 
   using InteractionScheme = mitk::InteractionSchemeSwitcher::InteractionScheme;
 
   QmitkInteractionSchemeToolBar(QWidget* parent = nullptr);
   ~QmitkInteractionSchemeToolBar() override;
 
   void SetInteractionEventHandler(mitk::InteractionEventHandler::Pointer interactionEventHandler);
 
-protected slots:
+protected Q_SLOTS:
 
-  void OnInteractionSchemeChanged();
   void AddButton(InteractionScheme id, const QString& toolName, const QIcon& icon, bool on = false);
+  void OnInteractionSchemeChanged();
 
 private:
 
   QActionGroup* m_ActionGroup;
 
   mitk::InteractionSchemeSwitcher::Pointer m_InteractionSchemeSwitcher;
   mitk::InteractionEventHandler::Pointer m_InteractionEventHandler;
 
 };
 
 #endif // QMITKINTERACTIONSCHEMETOOLBAR_H
diff --git a/Modules/QtWidgets/src/QmitkInteractionSchemeToolBar.cpp b/Modules/QtWidgets/src/QmitkInteractionSchemeToolBar.cpp
index 4b001600ad..383e3cdfcc 100644
--- a/Modules/QtWidgets/src/QmitkInteractionSchemeToolBar.cpp
+++ b/Modules/QtWidgets/src/QmitkInteractionSchemeToolBar.cpp
@@ -1,100 +1,106 @@
 /*============================================================================
 
 The Medical Imaging Interaction Toolkit (MITK)
 
 Copyright (c) German Cancer Research Center (DKFZ)
 All rights reserved.
 
 Use of this source code is governed by a 3-clause BSD license that can be
 found in the LICENSE file.
 
 ============================================================================*/
 
 #include "QmitkInteractionSchemeToolBar.h"
 
 #include <QActionGroup>
 
 QmitkInteractionSchemeToolBar::QmitkInteractionSchemeToolBar(QWidget* parent/* = nullptr*/)
   : QToolBar(parent)
   , m_ActionGroup(new QActionGroup(this))
   , m_InteractionSchemeSwitcher(nullptr)
   , m_InteractionEventHandler(nullptr)
 {
   QToolBar::setOrientation(Qt::Vertical);
   QToolBar::setIconSize(QSize(17, 17));
   QToolBar::setFixedWidth(33);
   m_ActionGroup->setExclusive(false); // allow having no action selected
 
   AddButton(InteractionScheme::PACSStandard, tr("Pointer"), QIcon(":/Qmitk/mm_pointer.png"), true);
   AddButton(InteractionScheme::PACSLevelWindow, tr("Level/Window"), QIcon(":/Qmitk/mm_contrast.png"));
   AddButton(InteractionScheme::PACSPan, tr("Pan"), QIcon(":/Qmitk/mm_pan.png"));
   AddButton(InteractionScheme::PACSScroll, tr("Scroll"), QIcon(":/Qmitk/mm_scroll.png"));
   AddButton(InteractionScheme::PACSZoom, tr("Zoom"), QIcon(":/Qmitk/mm_zoom.png"));
 
   m_InteractionSchemeSwitcher = mitk::InteractionSchemeSwitcher::New();
 }
 
+QmitkInteractionSchemeToolBar::~QmitkInteractionSchemeToolBar()
+{
+  // nothing here
+}
+
 void QmitkInteractionSchemeToolBar::SetInteractionEventHandler(mitk::InteractionEventHandler::Pointer interactionEventHandler)
 {
   if (interactionEventHandler == m_InteractionEventHandler)
   {
     return;
   }
 
   m_InteractionEventHandler = interactionEventHandler;
-  try
-  {
-    m_InteractionSchemeSwitcher->SetInteractionScheme(m_InteractionEventHandler, InteractionScheme::PACSStandard);
-  }
-  catch (const mitk::Exception&)
+  if (nullptr != m_InteractionSchemeSwitcher)
   {
-    return;
+    try
+    {
+      m_InteractionSchemeSwitcher->SetInteractionScheme(m_InteractionEventHandler, InteractionScheme::PACSStandard);
+    }
+    catch (const mitk::Exception&)
+    {
+      return;
+    }
   }
 }
 
 void QmitkInteractionSchemeToolBar::AddButton(InteractionScheme interactionScheme, const QString& toolName, const QIcon& icon, bool on)
 {
   QAction* action = new QAction(icon, toolName, this);
   action->setCheckable(true);
   action->setActionGroup(m_ActionGroup);
   action->setChecked(on);
   action->setData(interactionScheme);
-  connect(action, SIGNAL(triggered()), this, SLOT(OnInteractionSchemeChanged()));
+  connect(action, &QAction::triggered, this, &QmitkInteractionSchemeToolBar::OnInteractionSchemeChanged);
   QToolBar::addAction(action);
 }
 
-QmitkInteractionSchemeToolBar::~QmitkInteractionSchemeToolBar()
-{
-  // nothing here
-}
-
 void QmitkInteractionSchemeToolBar::OnInteractionSchemeChanged()
 {
   QAction* action = dynamic_cast<QAction*>(sender());
-  if (action)
+  if (nullptr != action)
   {
     for (auto actionIter : m_ActionGroup->actions())
     {
       if (actionIter != action)
       {
         actionIter->setChecked(false);
       }
     }
 
     InteractionScheme interactionScheme = static_cast<InteractionScheme>(action->data().toInt());
     // If the selected option is unchecked, use the base interaction with no primary tool
     if (!action->isChecked())
     {
       interactionScheme = InteractionScheme::PACSBase;
     }
 
-    try
-    {
-      m_InteractionSchemeSwitcher->SetInteractionScheme(m_InteractionEventHandler, interactionScheme);
-    }
-    catch (const mitk::Exception&)
+    if (nullptr != m_InteractionSchemeSwitcher)
     {
-      return;
+      try
+      {
+        m_InteractionSchemeSwitcher->SetInteractionScheme(m_InteractionEventHandler, interactionScheme);
+      }
+      catch (const mitk::Exception&)
+      {
+        return;
+      }
     }
   }
 }