diff --git a/Modules/IGTUI/Qmitk/QmitkTrackingSourcesCheckBoxPanelWidget.cpp b/Modules/IGTUI/Qmitk/QmitkTrackingSourcesCheckBoxPanelWidget.cpp
index d4eee2d70a..20a418bcb2 100644
--- a/Modules/IGTUI/Qmitk/QmitkTrackingSourcesCheckBoxPanelWidget.cpp
+++ b/Modules/IGTUI/Qmitk/QmitkTrackingSourcesCheckBoxPanelWidget.cpp
@@ -1,276 +1,276 @@
 /*===================================================================
 
 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 "QmitkTrackingSourcesCheckBoxPanelWidget.h"
 
 #include <QMessageBox>
 
 
 QmitkTrackingSourcesCheckBoxPanelWidget::QmitkTrackingSourcesCheckBoxPanelWidget(QWidget* parent)
 : QWidget(parent), m_Controls(NULL), m_SourceCheckboxes(NULL), m_NavigationDatas(NULL), m_SelectedIds(NULL)
 {
   this->CreateQtPartControl( this );
   m_SourceCheckboxes = new TrackingSourcesCheckboxes();
 }
 
 QmitkTrackingSourcesCheckBoxPanelWidget::~QmitkTrackingSourcesCheckBoxPanelWidget()
 {
   delete m_SelectedIds;
   delete m_SourceCheckboxes;
   delete m_NavigationDatas;
 }
 
 void QmitkTrackingSourcesCheckBoxPanelWidget::CreateQtPartControl(QWidget *parent)
 {
   if (!m_Controls)
   {
     // create GUI widgets
     m_Controls = new Ui::QmitkTrackingSourcesCheckBoxPanelWidgetControls;
     m_Controls->setupUi(parent);
 
     this->CreateConnections();
   }
 }
 
 void QmitkTrackingSourcesCheckBoxPanelWidget::CreateConnections()
 {
   connect( (QPushButton*) m_Controls->m_ActionButton, SIGNAL(toggled(bool)), this, SLOT(OnPerformActionClicked(bool)) ) ;
   connect( (QPushButton*) m_Controls->m_ActionButton, SIGNAL(clicked()), this, SLOT(OnPerformActionClicked()) ) ;
 }
 
 
 void QmitkTrackingSourcesCheckBoxPanelWidget::SetNavigationDatas(std::vector<mitk::NavigationData::Pointer>* navDatas)
 {
   if( navDatas != NULL )
     m_NavigationDatas = navDatas;
 }
 
 
 void QmitkTrackingSourcesCheckBoxPanelWidget::AddNavigationData(mitk::NavigationData::Pointer nd)
 {
   if(m_NavigationDatas == NULL)
     m_NavigationDatas = new std::vector<mitk::NavigationData::Pointer>();
 
   if( nd.IsNotNull() )
     m_NavigationDatas->push_back(nd);
 }
 
 bool QmitkTrackingSourcesCheckBoxPanelWidget::IsActionButtonChecked(){
   return m_Controls->m_ActionButton->isChecked();
 }
 
 
 const std::vector<int>* QmitkTrackingSourcesCheckBoxPanelWidget::GetSelectedTrackingSourcesIDs()
 {
   if(m_SelectedIds == NULL)
     m_SelectedIds = new std::vector<int>();
   else
     m_SelectedIds->clear();
 
   for (unsigned int i=0; i < m_SourceCheckboxes->size(); i++)
   {
     if(m_SourceCheckboxes->at(i)->isChecked())
       m_SelectedIds->push_back(i);
   }
 
   return m_SelectedIds;
 }
 
 void QmitkTrackingSourcesCheckBoxPanelWidget::ClearPanel()
 {
   while(m_Controls->m_GridLayout->count() > 0)
   {
     QWidget* actWidget = m_Controls->m_GridLayout->itemAt(0)->widget();
     m_Controls->m_GridLayout->removeWidget(actWidget);
     delete actWidget;
   }
 
   if(m_SourceCheckboxes != NULL)
     m_SourceCheckboxes->clear();
 
   if(m_NavigationDatas != NULL)
     m_NavigationDatas->clear();
 
 
 }
 
 void QmitkTrackingSourcesCheckBoxPanelWidget::ClearSelectedIDs()
 {
   if(m_SelectedIds != NULL && !m_SelectedIds->empty())
     m_SelectedIds->clear();
 }
 
 void QmitkTrackingSourcesCheckBoxPanelWidget::ShowSourceCheckboxes()
 {
   if( m_SourceCheckboxes != NULL )
     m_SourceCheckboxes->clear();
 
   if( m_NavigationDatas == NULL )
     return;
 
   QCheckBox* checkBox;
 
   int row = 0;
   int column;
 
   for(unsigned int i=0; i < m_NavigationDatas->size(); i++)  // puts a radiobutton for every tracking source output in a 2 columns QGridLayout
   {
     column = i % 4;
     if( i>0 && i%4==0 )
       row++;
 
     QString name(m_NavigationDatas->at(i).GetPointer()->GetName());
 
     checkBox = new QCheckBox(name, this);
 
     connect( checkBox, SIGNAL(toggled(bool)), this , SLOT(OnCheckboxClicked(bool)) );
 
     m_SourceCheckboxes->push_back(checkBox);
     m_Controls->m_GridLayout->addWidget(checkBox,row,column);
 
   }
 
 }
 
 void QmitkTrackingSourcesCheckBoxPanelWidget::EnableCheckboxes(bool enable)
 {
   for(unsigned int i=0; i< m_SourceCheckboxes->size(); i++)
   {
     m_SourceCheckboxes->at(i)->setEnabled(enable);
   }
 }
 
 void QmitkTrackingSourcesCheckBoxPanelWidget::SelectAll()
 {
   for(unsigned int i=0; i< m_SourceCheckboxes->size(); i++)
   {
     m_SourceCheckboxes->at(i)->setChecked(true);
   }
 }
 
 void QmitkTrackingSourcesCheckBoxPanelWidget::DeselectAll()
 {
   for(unsigned int i=0; i< m_SourceCheckboxes->size(); i++)
   {
     m_SourceCheckboxes->at(i)->setChecked(false);
   }
 }
 
 void QmitkTrackingSourcesCheckBoxPanelWidget::SelectCheckbox(unsigned int idx)
 {
   m_SourceCheckboxes->at(idx)->setChecked(true);
 }
 
 void QmitkTrackingSourcesCheckBoxPanelWidget::DeselectCheckbox(unsigned int idx)
 {
   m_SourceCheckboxes->at(idx)->setChecked(false);
 }
 
 
 void QmitkTrackingSourcesCheckBoxPanelWidget::OnCheckboxClicked(bool checked)
 {
   QCheckBox* sender = qobject_cast< QCheckBox* > (QObject::sender());
 
   if( sender == NULL )
     throw std::invalid_argument("No sender found!");
 
   int idx = -1;
 
   for(unsigned int i=0 ;i < m_SourceCheckboxes->size(); i++)
   {
     if(sender == m_SourceCheckboxes->at(i))
     {   idx=i;
     break;
     }
   }
 
   if(idx>-1)
   {
     if(checked)
       emit Selected(idx);
     else
       emit Deselected(idx);
   }
 
 }
 
 void QmitkTrackingSourcesCheckBoxPanelWidget::SetInfoText(QString text)
 {
   m_Controls->m_InfoLabel->setText(text);
 }
 
 void QmitkTrackingSourcesCheckBoxPanelWidget::SetActionPerformButtonText(QString text)
 {
   m_Controls->m_ActionButton->setText(text);
 }
 
 
 void QmitkTrackingSourcesCheckBoxPanelWidget::HideActionPerformButton(bool hide)
 {
   if(hide)
     m_Controls->m_ActionButton->hide();
   else
     m_Controls->m_ActionButton->show();
 }
 
 
 void QmitkTrackingSourcesCheckBoxPanelWidget::SetActionPerformButtonCheckable(bool checkable)
 {
   if(checkable)
     m_Controls->m_ActionButton->setCheckable(true);
   else
     m_Controls->m_ActionButton->setCheckable(false);
 }
 
 void QmitkTrackingSourcesCheckBoxPanelWidget::OnPerformActionClicked(bool toggled)
 {
   if(this->GetSelectedTrackingSourcesIDs()->empty())
   {
     m_Controls->m_ActionButton->setChecked(false);
     return;
   }
 
   if(toggled)
   {
     bool invalidND = false;
 
-    for(int i=0; i < this->GetSelectedTrackingSourcesIDs()->size(); ++i)
+    for(size_t i = 0; i < this->GetSelectedTrackingSourcesIDs()->size(); ++i)
     {
       if(!(m_NavigationDatas->at(this->GetSelectedTrackingSourcesIDs()->at(i))->IsDataValid()))
         invalidND = true;
     }
 
     if(invalidND)
     {
       QMessageBox::warning(NULL, "Invalid Tracking Data", "One or more instruments are in invalid tracking state! Requested action can not be performed!");
       m_Controls->m_ActionButton->setChecked(false);
       return;
     }
     emit PerformAction();
   }
   else
     emit StopAction();
 }
 
 void QmitkTrackingSourcesCheckBoxPanelWidget::OnPerformActionClicked()
 {
   if(this->GetSelectedTrackingSourcesIDs()->empty()){
     m_Controls->m_ActionButton->setChecked(false);
     return;
   }
 
   emit Action();
 }