diff --git a/Modules/IGTUI/Qmitk/QmitkToolTrackingStatusWidget.cpp b/Modules/IGTUI/Qmitk/QmitkToolTrackingStatusWidget.cpp
index a46f603f9c..0114f21af9 100644
--- a/Modules/IGTUI/Qmitk/QmitkToolTrackingStatusWidget.cpp
+++ b/Modules/IGTUI/Qmitk/QmitkToolTrackingStatusWidget.cpp
@@ -1,273 +1,274 @@
 /*===================================================================
 
 The Medical Imaging Interaction Toolkit (MITK)
 
 Copyright (c) German Cancer Research Center,
 Division of Medical and Biological Informatics.
 All rights reserved.
 
 This software is distributed WITHOUT ANY WARRANTY; without
 even the implied warranty of MERCHANTABILITY or FITNESS FOR
 A PARTICULAR PURPOSE.
 
 See LICENSE.txt or http://www.mitk.org for details.
 
 ===================================================================*/
 
 #include "QmitkToolTrackingStatusWidget.h"
 #include <usGetModuleContext.h>
 
 
 QmitkToolTrackingStatusWidget::QmitkToolTrackingStatusWidget(QWidget* parent)
-  : QWidget(parent), m_Controls(nullptr), m_StatusLabels(nullptr), m_NavigationDatas(nullptr), m_NavDatasNewFlag(false)
+  : QWidget(parent), m_Controls(nullptr), m_StatusLabels(nullptr), m_NavigationDatas(nullptr), m_NavDatasNewFlag(false), m_previewToolStorage(nullptr)
 {
   m_ShowPositions = false;
   m_ShowQuaternions = false;
   m_Alignment = Qt::AlignHCenter;
   m_Style = QmitkToolTrackingStatusWidget::VerticalUpperStyle;
 
   CreateQtPartControl( this );
 }
 
 void QmitkToolTrackingStatusWidget::SetStyle(QmitkToolTrackingStatusWidget::Style newStyle)
   {
   //set new style
   m_Style = newStyle;
 
   //update current labels to show them in the new style
   Refresh();
   }
 
 void QmitkToolTrackingStatusWidget::SetShowPositions(bool enable)
 {
   m_ShowPositions = enable;
 
   //update current labels
   Refresh();
 }
 
 void QmitkToolTrackingStatusWidget::SetShowQuaternions(bool enable)
 {
   m_ShowQuaternions = enable;
 
   //update current labels
   Refresh();
 }
 
 void QmitkToolTrackingStatusWidget::SetTextAlignment(Qt::AlignmentFlag alignment)
 {
   m_Alignment = alignment;
 
   //update current labels
   Refresh();
 }
 
 QmitkToolTrackingStatusWidget::~QmitkToolTrackingStatusWidget()
 {
+  m_Context->RemoveServiceListener(this, &QmitkToolTrackingStatusWidget::OnServiceEvent);
   //m_Controls = nullptr;
   if (m_StatusLabels!=nullptr) {delete m_StatusLabels;}
   if (m_NavigationDatas != nullptr)
   {
     m_NavigationDatas->clear();
     if (m_NavDatasNewFlag)
     {
       delete m_NavigationDatas;
-}
+    }
   }
 }
 
 void QmitkToolTrackingStatusWidget::CreateQtPartControl(QWidget *parent)
 {
   if (!m_Controls)
   {
     // create GUI widgets
     m_Controls = new Ui::QmitkToolTrackingStatusWidgetControls;
     m_Controls->setupUi(parent);
 
     this->CreateConnections();
 
     //add empty label
     AddEmptyLabel();
   }
   m_Context = us::GetModuleContext();
 
   std::string m_Filter = "(" + us::ServiceConstants::OBJECTCLASS() + "=" + "org.mitk.services.NavigationToolStorage" + ")";
 
   m_Context->AddServiceListener(this, &QmitkToolTrackingStatusWidget::OnServiceEvent, m_Filter);
 }
 
 void QmitkToolTrackingStatusWidget::OnServiceEvent(const us::ServiceEvent event)
 {
   if ((event.GetType() == us::ServiceEvent::MODIFIED) && (m_previewToolStorage.IsNotNull())) {this->PreShowTools(m_previewToolStorage);}
 }
 
 void QmitkToolTrackingStatusWidget::CreateConnections()
 {
 }
 
 void QmitkToolTrackingStatusWidget::SetNavigationDatas(std::vector<mitk::NavigationData::Pointer>* navDatas)
 {
   m_NavigationDatas = navDatas;
   m_previewToolStorage = nullptr;
 }
 
 void QmitkToolTrackingStatusWidget::AddNavigationData(mitk::NavigationData::Pointer nd)
 {
   if(m_NavigationDatas == nullptr)
   {
     m_NavigationDatas = new std::vector<mitk::NavigationData::Pointer>();
     m_NavDatasNewFlag = true;
     m_previewToolStorage = nullptr;
     }
 
   m_NavigationDatas->push_back(nd);
 }
 
 void QmitkToolTrackingStatusWidget::Refresh(int posPrecision, int quatPrecision)
 {
   if(m_NavigationDatas == nullptr || m_NavigationDatas->size() <= 0)
     {
     RemoveGuiLabels();
     AddEmptyLabel();
     return;
     }
 
   mitk::NavigationData* navData;
 
   for(unsigned int i = 0; i < m_NavigationDatas->size(); i++)
   {
     navData = m_NavigationDatas->at(i).GetPointer();
     QString name(navData->GetName());
     QString pos = "";
     QString quat = "";
     if (m_ShowPositions)
       {
       mitk::Point3D position = navData->GetPosition();
       pos = " [" + QString::number(position[0],'f',posPrecision) + ";" + QString::number(position[1],'f',posPrecision) + ";" + QString::number(position[2],'f',posPrecision) + "]";
       }
     if (m_ShowQuaternions)
       {
       mitk::Quaternion quaternion = navData->GetOrientation();
       quat = " / [qx:" + QString::number(quaternion.x(),'f',quatPrecision) + ";qy:" + QString::number(quaternion.y(),'f',quatPrecision) + ";qz:" + QString::number(quaternion.z(),'f',quatPrecision) + ";qr:" + QString::number(quaternion.r()) + "]";
       }
 
      if(!(m_StatusLabels->at(i)->text() == name+pos+quat))
         m_StatusLabels->at(i)->setText(name+pos+quat);
 
       if(navData->IsDataValid())
         m_StatusLabels->at(i)->setStyleSheet("QLabel{background-color: #8bff8b }");
       else
         m_StatusLabels->at(i)->setStyleSheet("QLabel{background-color: #ff7878 }");
   }
 }
 
 void QmitkToolTrackingStatusWidget::ShowStatusLabels()
 {
   RemoveGuiLabels();
 
   if(m_NavigationDatas == nullptr || m_NavigationDatas->size() <= 0)
     {
     RemoveGuiLabels();
     AddEmptyLabel();
     return;
     }
 
   m_StatusLabels = new QVector<QLabel*>();
   mitk::NavigationData* navData;
   QLabel* label;
 
   for(unsigned int i = 0; i < m_NavigationDatas->size(); i++)
   {
     navData = m_NavigationDatas->at(i).GetPointer();
 
     QString name(navData->GetName());
 
     label = new QLabel(name, this);
     label->setObjectName(name);
     label->setAlignment(m_Alignment | Qt::AlignVCenter);
     label->setFrameStyle(QFrame::Panel | QFrame::Sunken);
 
     m_StatusLabels->append(label);
     if (m_Style == QmitkToolTrackingStatusWidget::VerticalUpperStyle) 
       m_Controls->m_VerticalLayout->addWidget(m_StatusLabels->at(i));
     else m_Controls->m_GridLayout->addWidget(m_StatusLabels->at(i),i,0);
   }
 }
 
 void QmitkToolTrackingStatusWidget::PreShowTools(mitk::NavigationToolStorage::Pointer toolStorage)
 {
   RemoveGuiLabels();
   QLabel* label;
 
   for(unsigned int i = 0; i < toolStorage->GetToolCount(); i++)
   {
     QString name(toolStorage->GetTool(i)->GetToolName().c_str());
 
     label = new QLabel(name, this);
     label->setObjectName(name);
     label->setAlignment(m_Alignment | Qt::AlignVCenter);
     label->setFrameStyle(QFrame::Panel | QFrame::Sunken);
     label->setStyleSheet("QLabel{background-color: #dddddd }");
     if (m_Style == QmitkToolTrackingStatusWidget::VerticalUpperStyle) m_Controls->m_VerticalLayout->addWidget(label);
     else m_Controls->m_GridLayout->addWidget(label);
   }
   m_previewToolStorage = toolStorage;
 }
 
 void QmitkToolTrackingStatusWidget::RemoveStatusLabels()
 {
   //remove GUI elements
   RemoveGuiLabels();
 
   //clear members
   if(m_StatusLabels != nullptr && m_StatusLabels->size() > 0)
     {
     delete m_StatusLabels;
     m_StatusLabels = new QVector< QLabel* >();
     }
 
   if(m_NavigationDatas != nullptr && m_NavigationDatas->size() > 0)
     {
     if (m_NavDatasNewFlag)
     {
     delete m_NavigationDatas;
       m_NavDatasNewFlag = false;
     }
     m_NavigationDatas = new std::vector<mitk::NavigationData::Pointer>();
     m_NavDatasNewFlag = true;
     }
 
   //add empty label
   AddEmptyLabel();
 }
 
 void QmitkToolTrackingStatusWidget::RemoveGuiLabels()
 {
   while(m_Controls->m_GridLayout->count() > 0 || m_Controls->m_VerticalLayout->count() > 0)
   {
     if (m_Controls->m_GridLayout->count() > 0)
     {
       QWidget* actWidget = m_Controls->m_GridLayout->itemAt(0)->widget();
       m_Controls->m_GridLayout->removeWidget(actWidget);
       delete actWidget;
     }
     else if (m_Controls->m_VerticalLayout->count() > 0)
     {
       QWidget* actWidget = m_Controls->m_VerticalLayout->itemAt(0)->widget();
       m_Controls->m_VerticalLayout->removeWidget(actWidget);
       delete actWidget;
     }
   }
 }
 
 void QmitkToolTrackingStatusWidget::AddEmptyLabel()
 {
   //add a label which tells that no tools are loaded yet
   QLabel* label = new QLabel("No tools loaded yet.", this);
   label->setObjectName("No tools loaded yet.");
   label->setAlignment(m_Alignment | Qt::AlignVCenter);
   label->setFrameStyle(QFrame::Panel | QFrame::Sunken);
   label->setStyleSheet("QLabel{background-color: #dddddd }");
   if (m_Style == QmitkToolTrackingStatusWidget::VerticalUpperStyle) m_Controls->m_VerticalLayout->addWidget(label);
   else m_Controls->m_GridLayout->addWidget(label);
 }