diff --git a/Modules/SegmentationUI/Qmitk/QmitkMultiLabelTreeModel.cpp b/Modules/SegmentationUI/Qmitk/QmitkMultiLabelTreeModel.cpp
index 13779785b3..97d0ab5822 100644
--- a/Modules/SegmentationUI/Qmitk/QmitkMultiLabelTreeModel.cpp
+++ b/Modules/SegmentationUI/Qmitk/QmitkMultiLabelTreeModel.cpp
@@ -1,922 +1,924 @@
 /*============================================================================
 
 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 "QmitkMultiLabelTreeModel.h"
 
 #include "mitkRenderingManager.h"
 
 #include "QmitkStyleManager.h"
 
 
 class QmitkMultiLabelSegTreeItem
 {
 public:
   enum class ItemType
   {
     Group,
     Label,
     Instance
   };
 
   QmitkMultiLabelSegTreeItem()
   {
   };
 
   explicit QmitkMultiLabelSegTreeItem(ItemType type, QmitkMultiLabelSegTreeItem* parentItem,
     mitk::Label* label = nullptr, std::string className = ""): m_ItemType(type), m_Label(label), m_parentItem(parentItem), m_ClassName(className)
   {
   };
 
   ~QmitkMultiLabelSegTreeItem()
   {
     for (auto item : m_childItems)
     {
       delete item;
     }
   };
 
   void AppendChild(QmitkMultiLabelSegTreeItem* child)
   {
       m_childItems.push_back(child);
   };
 
   void RemoveChild(std::size_t row)
   {
     if (row < m_childItems.size())
     {
       delete m_childItems[row];
       m_childItems.erase(m_childItems.begin() + row);
     }
   };
 
   int Row() const
   {
     if (m_parentItem)
     {
       auto finding = std::find(m_parentItem->m_childItems.begin(), m_parentItem->m_childItems.end(), this);
       if (finding != m_parentItem->m_childItems.end())
       {
         return std::distance(m_parentItem->m_childItems.begin(), finding);
       }
     }
 
     return 0;
   };
 
   QmitkMultiLabelSegTreeItem* ParentItem()
   {
     return m_parentItem;
   };
 
   const QmitkMultiLabelSegTreeItem* ParentItem() const
   {
     return m_parentItem;
   };
 
   const QmitkMultiLabelSegTreeItem* NextSibblingItem() const
   {
     if (m_parentItem)
     {
       const auto row = this->Row()+1;
       if (row < m_parentItem->m_childItems.size())
         return m_parentItem->m_childItems[row];
     }
 
     return nullptr;
   };
 
   const QmitkMultiLabelSegTreeItem* PrevSibblingItem() const
   {
     if (m_parentItem)
     {
       const auto row = this->Row();
       if (row > 0)
         return m_parentItem->m_childItems[row-1];
     }
 
     return nullptr;
   };
 
   const QmitkMultiLabelSegTreeItem* RootItem() const
   {
     auto item = this;
     while (item->m_parentItem != nullptr)
     {
       item = item->m_parentItem;
     }
     return item;
   };
 
   std::size_t GetGroupID() const
   {
     auto root = this->RootItem();
     auto item = this;
     if (root == this) return 0;
 
     while (root != item->m_parentItem)
     {
       item = item->m_parentItem;
     }
 
     auto iter = std::find(root->m_childItems.begin(), root->m_childItems.end(), item);
 
     if (root->m_childItems.end() == iter) mitkThrow() << "Invalid internal state of QmitkMultiLabelTreeModel. Root does not have an currentItem as child that has root as parent.";
 
     return std::distance(root->m_childItems.begin(), iter);
   }
 
   bool HandleAsInstance() const
   {
     return (ItemType::Instance == m_ItemType) || ((ItemType::Label == m_ItemType) && (m_childItems.size() == 1));
   }
 
   mitk::Label* GetLabel() const
   {
     if (ItemType::Instance == m_ItemType)
     {
       return m_Label;
     }
     if (ItemType::Label == m_ItemType)
     {
       if (m_childItems.empty()) mitkThrow() << "Invalid internal state of QmitkMultiLabelTreeModel. Internal label currentItem has no instance currentItem.";
       return m_childItems[0]->GetLabel();
     }
 
     return nullptr;
   };
 
   mitk::LabelSetImage::LabelValueType GetLabelValue() const
   {
     auto label = this->GetLabel();
 
     if (nullptr == label)
     {
       mitkThrow() << "Invalid internal state of QmitkMultiLabelTreeModel. Called GetLabelValue on an group currentItem.";
     }
 
     return label->GetValue();
   };
 
   QmitkMultiLabelSegTreeItem* m_parentItem = nullptr;
   std::vector<QmitkMultiLabelSegTreeItem*> m_childItems;
   ItemType m_ItemType = ItemType::Group;
   mitk::Label::Pointer m_Label;
   std::string m_ClassName;
 };
 
 
 
 QModelIndex GetIndexByItem(const QmitkMultiLabelSegTreeItem* start, const QmitkMultiLabelTreeModel* model)
 {
   QModelIndex parentIndex = QModelIndex();
   if (nullptr != start->m_parentItem)
   {
     parentIndex = GetIndexByItem(start->m_parentItem, model);
   }
   else
   {
     return parentIndex;
   }
 
   return model->index(start->Row(), 0, parentIndex);
 }
 
 QmitkMultiLabelSegTreeItem* GetGroupItem(QmitkMultiLabelTreeModel::SpatialGroupIndexType groupIndex, QmitkMultiLabelSegTreeItem* root)
 {
   if (nullptr != root && groupIndex < root->m_childItems.size())
   {
     return root->m_childItems[groupIndex];
   }
 
   return nullptr;
 }
 
 QmitkMultiLabelSegTreeItem* GetInstanceItem(QmitkMultiLabelTreeModel::LabelValueType labelValue, QmitkMultiLabelSegTreeItem* root)
 {
   QmitkMultiLabelSegTreeItem* result = nullptr;
 
   for (auto item : root->m_childItems)
   {
     result = GetInstanceItem(labelValue, item);
     if (nullptr != result) return result;
   }
 
   if (root->m_ItemType == QmitkMultiLabelSegTreeItem::ItemType::Instance && root->GetLabelValue() == labelValue)
   {
     return root;
   }
 
   return nullptr;
 }
 
 const QmitkMultiLabelSegTreeItem* GetFirstInstanceLikeItem(const QmitkMultiLabelSegTreeItem* startItem)
 {
   const QmitkMultiLabelSegTreeItem* result = nullptr;
 
   if (nullptr != startItem)
   {
     if (startItem->HandleAsInstance())
     {
       result = startItem;
     }
     else if (!startItem->m_childItems.empty())
     {
       result = GetFirstInstanceLikeItem(startItem->m_childItems.front());
     }
   }
 
   return result;
 }
 
 QmitkMultiLabelSegTreeItem* GetLabelItemInGroup(const std::string& labelName, QmitkMultiLabelSegTreeItem* group)
 {
   if (nullptr != group)
   {
     auto predicate = [labelName](const QmitkMultiLabelSegTreeItem* item) { return labelName == item->m_ClassName; };
     auto finding = std::find_if(group->m_childItems.begin(), group->m_childItems.end(), predicate);
     if (group->m_childItems.end() != finding)
     {
       return *finding;
     }
   }
 
   return nullptr;
 }
 
 QmitkMultiLabelTreeModel::QmitkMultiLabelTreeModel(QObject *parent) : QAbstractItemModel(parent)
 , m_Observed(false)
 {
   m_RootItem = std::make_unique<QmitkMultiLabelSegTreeItem>();
 }
 
 QmitkMultiLabelTreeModel ::~QmitkMultiLabelTreeModel()
 {
   this->SetSegmentation(nullptr);
 };
 
 int QmitkMultiLabelTreeModel::columnCount(const QModelIndex& /*parent*/) const
 {
   return 4;
 }
 
 int QmitkMultiLabelTreeModel::rowCount(const QModelIndex &parent) const
 {
   if (parent.column() > 0)
     return 0;
 
   if (m_Segmentation.IsNull())
     return 0;
 
   QmitkMultiLabelSegTreeItem* parentItem = m_RootItem.get();
 
   if (parent.isValid())
     parentItem = static_cast<QmitkMultiLabelSegTreeItem *>(parent.internalPointer());
 
   if (parentItem->HandleAsInstance())
   {
     return 0;
   }
 
   return parentItem->m_childItems.size();
 }
 
 QVariant QmitkMultiLabelTreeModel::data(const QModelIndex &index, int role) const
 {
   if (!index.isValid())
     return QVariant();
 
   auto item = static_cast<QmitkMultiLabelSegTreeItem*>(index.internalPointer());
 
   if (!item)
     return QVariant();
 
   if (role == Qt::DisplayRole||role == Qt::EditRole)
   {
     if (TableColumns::NAME_COL == index.column())
     {
       switch (item->m_ItemType)
       {
         case QmitkMultiLabelSegTreeItem::ItemType::Group:
           return QVariant(QString("Group ")+QString::number(item->GetGroupID()));
         case QmitkMultiLabelSegTreeItem::ItemType::Label:
         {
           auto label = item->GetLabel();
           if (nullptr == label) mitkThrow() << "Invalid internal state. QmitkMultiLabelTreeModel currentItem is refering to a label that does not exist.";
           return QVariant(QString::fromStdString(label->GetName()));
         }
         case QmitkMultiLabelSegTreeItem::ItemType::Instance:
           return QVariant(QString("Instance #") + QString::number(item->GetLabelValue()));
       }
     }
     else
     {
       if (item->HandleAsInstance())
       {
         auto label = item->GetLabel();
 
         if (TableColumns::LOCKED_COL == index.column())
         {
           return QVariant(label->GetLocked());
         }
         else if (TableColumns::COLOR_COL == index.column())
         {
           return QVariant(QColor(label->GetColor().GetRed() * 255, label->GetColor().GetGreen() * 255, label->GetColor().GetBlue() * 255));
         }
         else if (TableColumns::VISIBLE_COL == index.column())
         {
           return QVariant(label->GetVisible());
         }
       }
       else
       {
 
       }
     }
   }
   else if (role == ItemModelRole::LabelDataRole)
   {
     auto label = item->GetLabel();
     if (nullptr!=label)  return QVariant::fromValue<void*>(label);
   }
   else if (role == ItemModelRole::LabelValueRole)
   {
     auto label = item->GetLabel();
     if (nullptr != label)  return QVariant(label->GetValue());
   }
   else if (role == ItemModelRole::LabelInstanceDataRole)
   {
     if (item->HandleAsInstance())
     {
       auto label = item->GetLabel();
       return QVariant::fromValue<void*>(label);
     }
   }
   else if (role == ItemModelRole::LabelInstanceValueRole)
   {
     if (item->HandleAsInstance())
     {
       auto label = item->GetLabel();
       return QVariant(label->GetValue());
     }
   }
 
   return QVariant();
 }
 
 mitk::Color QtToMitk(const QColor& color)
 {
   mitk::Color mitkColor;
 
   mitkColor.SetRed(color.red() / 255.0f);
   mitkColor.SetGreen(color.green() / 255.0f);
   mitkColor.SetBlue(color.blue() / 255.0f);
 
   return mitkColor;
 }
 
 bool QmitkMultiLabelTreeModel::setData(const QModelIndex& index, const QVariant& value, int role)
 {
   if (!index.isValid())
     return false;
 
   auto item = static_cast<QmitkMultiLabelSegTreeItem*>(index.internalPointer());
 
   if (!item)
     return false;
 
   if (role == Qt::EditRole)
   {
     if (TableColumns::NAME_COL != index.column())
     {
       if (item->HandleAsInstance())
       {
         auto label = item->GetLabel();
 
         if (TableColumns::LOCKED_COL == index.column())
         {
           label->SetLocked(value.toBool());
         }
         else if (TableColumns::COLOR_COL == index.column())
         {
           label->SetColor(QtToMitk(value.value<QColor>()));
         }
         else if (TableColumns::VISIBLE_COL == index.column())
         {
           label->SetVisible(value.toBool());
         }
         auto groupID = m_Segmentation->GetGroupIndexOfLabel(label->GetValue());
         m_Segmentation->GetLabelSet(groupID)->UpdateLookupTable(label->GetValue());
         m_Segmentation->Modified();
         mitk::RenderingManager::GetInstance()->RequestUpdateAll();
       }
       else
       {
 
       }
       return true;
     }
   }
   return false;
 }
 
 QModelIndex QmitkMultiLabelTreeModel::index(int row, int column, const QModelIndex &parent) const
 {
   if (!hasIndex(row, column, parent))
     return QModelIndex();
 
   auto parentItem = m_RootItem.get();
 
   if (parent.isValid())
     parentItem = static_cast<QmitkMultiLabelSegTreeItem *>(parent.internalPointer());
 
   QmitkMultiLabelSegTreeItem *childItem = parentItem->m_childItems[row];
   if (childItem)
     return createIndex(row, column, childItem);
   else
     return QModelIndex();
 }
 
 QModelIndex QmitkMultiLabelTreeModel::indexOfLabel(mitk::Label::PixelType labelValue) const
 {
   if (labelValue == mitk::LabelSetImage::UnlabeledLabelValue) return QModelIndex();
   auto relevantItem = GetInstanceItem(labelValue, this->m_RootItem.get());
 
   if (nullptr == relevantItem) QModelIndex();
 
   auto labelItem = relevantItem->ParentItem();
 
   if (labelItem->m_childItems.size() == 1)
   { //was the only instance of the label, therefor return the label item instat.
     relevantItem = labelItem;
   }
 
   return GetIndexByItem(relevantItem, this);
 }
 
 QModelIndex QmitkMultiLabelTreeModel::indexOfGroup(mitk::LabelSetImage::SpatialGroupIndexType groupIndex) const
 {
   auto relevantItem = GetGroupItem(groupIndex, this->m_RootItem.get());
 
   if (nullptr == relevantItem) QModelIndex();
 
   return GetIndexByItem(relevantItem, this);
 }
 
 QModelIndex QmitkMultiLabelTreeModel::parent(const QModelIndex &child) const
 {
   if (!child.isValid())
     return QModelIndex();
 
   QmitkMultiLabelSegTreeItem *childItem = static_cast<QmitkMultiLabelSegTreeItem *>(child.internalPointer());
   QmitkMultiLabelSegTreeItem *parentItem = childItem->ParentItem();
 
   if (parentItem == m_RootItem.get())
     return QModelIndex();
 
   return createIndex(parentItem->Row(), 0, parentItem);
 }
 
 QModelIndex QmitkMultiLabelTreeModel::ClosestLabelInstanceIndex(const QModelIndex& currentIndex) const
 {
   if (!currentIndex.isValid()) return QModelIndex();
 
   auto currentItem = static_cast<const QmitkMultiLabelSegTreeItem*>(currentIndex.internalPointer());
   if (!currentItem) return QModelIndex();
 
   if (currentItem->RootItem() != this->m_RootItem.get()) mitkThrow() << "Invalid call. Passed currentIndex does not seem to be a valid index of this model. It is either outdated or from another model.";
 
   const QmitkMultiLabelSegTreeItem* resultItem = nullptr;
   auto searchItem = currentItem;
   const auto rootItem = currentItem->RootItem();
 
   while (searchItem != rootItem)
   {
     resultItem = GetFirstInstanceLikeItem(searchItem->NextSibblingItem());
     if (nullptr != resultItem) break;
 
     //no next closest label instance on this level -> check for closest before
     resultItem = GetFirstInstanceLikeItem(searchItem->PrevSibblingItem());
     if (nullptr != resultItem) break;
 
     //no closest label instance before current on this level -> moeve one level up
     searchItem = searchItem->ParentItem();
   }
 
   if (nullptr == resultItem)
     return QModelIndex();
 
   return GetIndexByItem(resultItem, this);
 }
 
 QModelIndex QmitkMultiLabelTreeModel::FirstLabelInstanceIndex(const QModelIndex& currentIndex) const
 {
   const QmitkMultiLabelSegTreeItem* currentItem = nullptr;
 
   if (!currentIndex.isValid())
   {
     currentItem = this->m_RootItem.get();
   }
   else
   {
     currentItem = static_cast<const QmitkMultiLabelSegTreeItem*>(currentIndex.internalPointer());
   }
 
   if (!currentItem) return QModelIndex();
 
   if (currentItem->RootItem() != this->m_RootItem.get()) mitkThrow() << "Invalid call. Passed currentIndex does not seem to be a valid index of this model. It is either outdated or from another model.";
 
   const QmitkMultiLabelSegTreeItem* resultItem = nullptr;
   resultItem = GetFirstInstanceLikeItem(currentItem);
 
   if (nullptr == resultItem)
     return QModelIndex();
 
   return GetIndexByItem(resultItem, this);
 }
 
 ///** Returns the index to the next node in the tree that behaves like an instance (label node with only one instance
 //or instance node). If current index is at the end, an invalid index is returned.*/
 //QModelIndex QmitkMultiLabelTreeModel::PrevLabelInstanceIndex(const QModelIndex& currentIndex) const;
 
 
 Qt::ItemFlags QmitkMultiLabelTreeModel::flags(const QModelIndex &index) const
 {
   if (!index.isValid())
     return Qt::NoItemFlags;
 
   if (!index.isValid())
     return Qt::NoItemFlags;
 
   auto item = static_cast<QmitkMultiLabelSegTreeItem*>(index.internalPointer());
 
   if (!item)
     return Qt::NoItemFlags;
 
   if (TableColumns::NAME_COL != index.column())
   {
     if (item->HandleAsInstance() &&
       ((TableColumns::VISIBLE_COL == index.column() && m_AllowVisibilityModification) ||
        (TableColumns::COLOR_COL == index.column() && m_AllowVisibilityModification) || //m_AllowVisibilityModification controls visibility and color
        (TableColumns::LOCKED_COL == index.column() && m_AllowLockModification)))
     {
       return Qt::ItemIsEnabled | Qt::ItemIsEditable;
     }
     else
     {
       return Qt::ItemIsEnabled;
     }
     return true;
   }
   else
   {
     if (item->HandleAsInstance())
     {
       return Qt::ItemIsEnabled | Qt::ItemIsSelectable;
     }
     else
     {
       return Qt::ItemIsEnabled;
     }
     return true;
   }
 
   return Qt::NoItemFlags;
 }
 
 QVariant QmitkMultiLabelTreeModel::headerData(int section, Qt::Orientation orientation, int role) const
 {
   if ((Qt::DisplayRole == role) && (Qt::Horizontal == orientation))
   {
     if (TableColumns::NAME_COL == section)
     {
       return "Name";
     }
     else if (TableColumns::LOCKED_COL == section)
     {
       return "Locked";
     }
     else if (TableColumns::COLOR_COL == section)
     {
       return "Color";
     }
     else if (TableColumns::VISIBLE_COL == section)
     {
       return "Visibility";
     }
   }
   return QVariant();
 }
 
 const mitk::LabelSetImage* QmitkMultiLabelTreeModel::GetSegmentation() const
 {
   return m_Segmentation;
 }
 
 
 void QmitkMultiLabelTreeModel::SetSegmentation(mitk::LabelSetImage* segmentation)
 {
   if (m_Segmentation != segmentation)
   {
     this->RemoveObserver();
     this->m_Segmentation = segmentation;
     this->AddObserver();
 
     this->UpdateInternalTree();
   }
 }
 
 
 /**Helper function that adds a labek into the item tree. Passes back the new created instance iten*/
 QmitkMultiLabelSegTreeItem* AddLabelToGroupTree(mitk::Label* label, QmitkMultiLabelSegTreeItem* groupItem, bool& newLabelItemCreated)
 {
   if (nullptr == groupItem) return nullptr;
   if (nullptr == label) return nullptr;
 
   newLabelItemCreated = false;
 
   std::set<std::string> labelNames;
   for (auto labelItem : groupItem->m_childItems)
   {
     labelNames.emplace(labelItem->GetLabel()->GetName());
   }
 
   QmitkMultiLabelSegTreeItem* labelItem = nullptr;
   auto finding = labelNames.find(label->GetName());
   if (finding != labelNames.end())
   { //other label with same name exists
     labelItem = groupItem->m_childItems[std::distance(labelNames.begin(), finding)];
   }
   else
   {
     newLabelItemCreated = true;
     labelItem = new QmitkMultiLabelSegTreeItem(QmitkMultiLabelSegTreeItem::ItemType::Label, groupItem, nullptr, label->GetName());
 
     auto predicate = [label](const std::string& name) { return name > label->GetName(); };
     auto insertFinding = std::find_if(labelNames.begin(), labelNames.end(), predicate);
 
     groupItem->m_childItems.insert(groupItem->m_childItems.begin() + std::distance(labelNames.begin(), insertFinding), labelItem);
   }
 
   auto instanceItem = new QmitkMultiLabelSegTreeItem(QmitkMultiLabelSegTreeItem::ItemType::Instance, labelItem, label);
 
   auto predicate = [label](const QmitkMultiLabelSegTreeItem* item) { return item->GetLabelValue() > label->GetValue(); };
   auto insertFinding = std::find_if(labelItem->m_childItems.begin(), labelItem->m_childItems.end(), predicate);
   labelItem->m_childItems.insert(labelItem->m_childItems.begin() + std::distance(labelItem->m_childItems.begin(), insertFinding), instanceItem);
 
   return instanceItem;
 }
 
 void QmitkMultiLabelTreeModel::GenerateInternalGroupTree(unsigned int groupID, QmitkMultiLabelSegTreeItem* groupItem)
 {
   auto labelSet = m_Segmentation->GetLabelSet(groupID);
 
   for (auto lIter = labelSet->IteratorConstBegin(); lIter != labelSet->IteratorConstEnd(); lIter++)
   {
     if (lIter->first== mitk::LabelSetImage::UnlabeledLabelValue || lIter->second == m_Segmentation->GetExteriorLabel()) continue;
 
     bool newItemCreated = false;
     AddLabelToGroupTree(lIter->second, groupItem, newItemCreated);
   }
 }
 
 QmitkMultiLabelSegTreeItem* QmitkMultiLabelTreeModel::GenerateInternalTree()
 {
   auto rootItem = new QmitkMultiLabelSegTreeItem();
 
   if (m_Segmentation.IsNotNull())
   {
     for (unsigned int groupID = 0; groupID < m_Segmentation->GetNumberOfLayers(); ++groupID)
     {
       auto groupItem = new QmitkMultiLabelSegTreeItem(QmitkMultiLabelSegTreeItem::ItemType::Group, rootItem);
       rootItem->AppendChild(groupItem);
 
       GenerateInternalGroupTree(groupID, groupItem);
     }
   }
 
   return rootItem;
 }
 
 void QmitkMultiLabelTreeModel::UpdateInternalTree()
 {
   emit beginResetModel();
   auto newTree = this->GenerateInternalTree();
   this->m_RootItem.reset(newTree);
   emit endResetModel();
   emit modelChanged();
 }
 
 void QmitkMultiLabelTreeModel::AddObserver()
 {
   if (this->m_Segmentation.IsNotNull())
   {
     if (m_Observed)
     {
       MITK_DEBUG << "Invalid observer state in QmitkMultiLabelTreeModel. There is already a registered observer. Internal logic is not correct. May be an old observer was not removed.";
     }
 
     this->m_Segmentation->AddLabelAddedListener(mitk::MessageDelegate1<QmitkMultiLabelTreeModel, LabelValueType>(
       this, &QmitkMultiLabelTreeModel::OnLabelAdded));
     this->m_Segmentation->AddLabelModifiedListener(mitk::MessageDelegate1<QmitkMultiLabelTreeModel, LabelValueType>(
       this, &QmitkMultiLabelTreeModel::OnLabelModified));
     this->m_Segmentation->AddLabelRemovedListener(mitk::MessageDelegate1<QmitkMultiLabelTreeModel, LabelValueType>(
       this, &QmitkMultiLabelTreeModel::OnLabelRemoved));
     this->m_Segmentation->AddGroupAddedListener(mitk::MessageDelegate1<QmitkMultiLabelTreeModel, SpatialGroupIndexType>(
       this, &QmitkMultiLabelTreeModel::OnGroupAdded));
     this->m_Segmentation->AddGroupModifiedListener(mitk::MessageDelegate1<QmitkMultiLabelTreeModel, SpatialGroupIndexType>(
       this, &QmitkMultiLabelTreeModel::OnGroupModified));
     this->m_Segmentation->AddGroupRemovedListener(mitk::MessageDelegate1<QmitkMultiLabelTreeModel, SpatialGroupIndexType>(
       this, &QmitkMultiLabelTreeModel::OnGroupRemoved));
     m_Observed = true;
   }
 }
 
 void QmitkMultiLabelTreeModel::RemoveObserver()
 {
   if (this->m_Segmentation.IsNotNull())
   {
     this->m_Segmentation->RemoveLabelAddedListener(mitk::MessageDelegate1<QmitkMultiLabelTreeModel, LabelValueType>(
       this, &QmitkMultiLabelTreeModel::OnLabelAdded));
     this->m_Segmentation->RemoveLabelModifiedListener(mitk::MessageDelegate1<QmitkMultiLabelTreeModel, LabelValueType>(
       this, &QmitkMultiLabelTreeModel::OnLabelModified));
     this->m_Segmentation->RemoveLabelRemovedListener(mitk::MessageDelegate1<QmitkMultiLabelTreeModel, LabelValueType>(
       this, &QmitkMultiLabelTreeModel::OnLabelRemoved));
     this->m_Segmentation->RemoveGroupAddedListener(mitk::MessageDelegate1<QmitkMultiLabelTreeModel, SpatialGroupIndexType>(
       this, &QmitkMultiLabelTreeModel::OnGroupAdded));
     this->m_Segmentation->RemoveGroupModifiedListener(mitk::MessageDelegate1<QmitkMultiLabelTreeModel, SpatialGroupIndexType>(
       this, &QmitkMultiLabelTreeModel::OnGroupModified));
     this->m_Segmentation->RemoveGroupRemovedListener(mitk::MessageDelegate1<QmitkMultiLabelTreeModel, SpatialGroupIndexType>(
       this, &QmitkMultiLabelTreeModel::OnGroupRemoved));
   }
   m_Observed = false;
 }
 
 void QmitkMultiLabelTreeModel::OnLabelAdded(LabelValueType labelValue)
 {
   SpatialGroupIndexType groupIndex = 0;
   if (m_Segmentation->IsLabeInGroup(labelValue, groupIndex))
   {
     auto label = m_Segmentation->GetLabel(labelValue);
     if (nullptr == label) mitkThrow() << "Invalid internal state. Segmentation signaled the addition of an label that does not exist in the segmentation. Invalid label value:" << labelValue;
     if (label == m_Segmentation->GetExteriorLabel()) return;
 
     auto groupItem = GetGroupItem(groupIndex, this->m_RootItem.get());
 
     bool newLabelCreated = false;
     auto instanceItem = AddLabelToGroupTree(label, groupItem, newLabelCreated);
 
     if (newLabelCreated)
     {
       if (groupItem->m_childItems.size() == 1)
       { //first label added
         auto groupIndex = GetIndexByItem(groupItem, this);
         emit dataChanged(groupIndex, groupIndex);
       }
       else
       { //whole new label level added to group item
         auto groupIndex = GetIndexByItem(groupItem, this);
         this->beginInsertRows(groupIndex, instanceItem->ParentItem()->Row(), instanceItem->ParentItem()->Row());
         this->endInsertRows();
       }
     }
     else
     {
       if (instanceItem->ParentItem()->m_childItems.size() < 3)
       { //second instance item was added, so label item will now able to colapse
         // -> the whole label node has to be updated.
         auto labelIndex = GetIndexByItem(instanceItem->ParentItem(), this);
         emit dataChanged(labelIndex, labelIndex);
+        this->beginInsertRows(labelIndex, 0, instanceItem->ParentItem()->m_childItems.size()-1);
+        this->endInsertRows();
       }
       else
       {
         // instance item was added to existing label item with multiple instances
         //-> just notify the row insertion
         auto labelIndex = GetIndexByItem(instanceItem->ParentItem(), this);
         this->beginInsertRows(labelIndex, instanceItem->Row(), instanceItem->Row());
         this->endInsertRows();
       }
     }
   }
   else
   {
     mitkThrow() << "Group less labels are not supported in the current implementation.";
   }
 }
 
 void QmitkMultiLabelTreeModel::OnLabelModified(LabelValueType labelValue)
 {
   if (labelValue == m_Segmentation->GetExteriorLabel()->GetValue()) return;
 
   auto instanceItem = GetInstanceItem(labelValue, this->m_RootItem.get());
 
   if (nullptr == instanceItem)
   {
     mitkThrow() << "Internal invalid state. QmitkMultiLabelTreeModel recieved a LabelModified signal for a label that is not represented in the model. Invalid label: " << labelValue;
   }
 
   auto labelItem = instanceItem->ParentItem();
 
   if (labelItem->m_ClassName == instanceItem->GetLabel()->GetName())
   { //only the state of the label changed, but not its position in the model tree.
 
     auto index = GetIndexByItem(labelItem, this);
     emit dataChanged(index, index);
   }
   else
   { //the name of the label changed and thus its place in the model tree, delete the current item and add a new one
     this->OnLabelRemoved(labelValue);
     this->OnLabelAdded(labelValue);
   }
 }
 
 void QmitkMultiLabelTreeModel::OnLabelRemoved(LabelValueType labelValue)
 {
   if (labelValue == m_Segmentation->GetExteriorLabel()->GetValue()) return;
   auto instanceItem = GetInstanceItem(labelValue, this->m_RootItem.get());
 
   if (nullptr == instanceItem) mitkThrow() << "Internal invalid state. QmitkMultiLabelTreeModel recieved a LabelRemoved signal for a label that is not represented in the model. Invalid label: " << labelValue;
 
   auto labelItem = instanceItem->ParentItem();
 
   if (labelItem->m_childItems.size() > 2)
   {
     auto labelIndex = GetIndexByItem(labelItem, this);
     this->beginRemoveRows(labelIndex, instanceItem->Row(), instanceItem->Row());
     labelItem->RemoveChild(instanceItem->Row());
     this->endRemoveRows();
   }
   else if (labelItem->m_childItems.size() == 2)
   { //After removal only one label is left -> the whole label node is about to be changed (no instances are shown any more).
     auto labelIndex = GetIndexByItem(labelItem, this);
     this->beginRemoveRows(labelIndex, instanceItem->Row(), instanceItem->Row());
     labelItem->RemoveChild(instanceItem->Row());
     this->endRemoveRows();
     emit dataChanged(labelIndex, labelIndex);
   }
   else
   { //was the only instance of the label, therefor also remove the label node from the tree.
     auto groupItem = labelItem->ParentItem();
     auto groupIndex = GetIndexByItem(groupItem, this);
     this->beginRemoveRows(groupIndex, labelItem->Row(), labelItem->Row());
     groupItem->RemoveChild(labelItem->Row());
     this->endRemoveRows();
   }
 }
 
 void QmitkMultiLabelTreeModel::OnGroupAdded(SpatialGroupIndexType groupIndex)
 {
   if (m_ShowGroups)
   {
     this->beginInsertRows(QModelIndex(), groupIndex, groupIndex);
     auto rootItem = m_RootItem.get();
     auto groupItem = new QmitkMultiLabelSegTreeItem(QmitkMultiLabelSegTreeItem::ItemType::Group, rootItem);
     rootItem->AppendChild(groupItem);
     this->GenerateInternalGroupTree(groupIndex, groupItem);
     this->endInsertRows();
   }
 }
 
 void QmitkMultiLabelTreeModel::OnGroupModified(SpatialGroupIndexType groupIndex)
 {
   //currently not needed
 }
 
 void QmitkMultiLabelTreeModel::OnGroupRemoved(SpatialGroupIndexType groupIndex)
 {
   if (m_ShowGroups)
   {
     this->beginRemoveRows(QModelIndex(), groupIndex, groupIndex);
     auto root = m_RootItem.get();
     root->RemoveChild(groupIndex);
     this->endRemoveRows();
   }
 }
 
 void QmitkMultiLabelTreeModel::SetAllowVisibilityModification(bool vmod)
 {
   m_AllowVisibilityModification = vmod;
 }
 
 bool QmitkMultiLabelTreeModel::GetAllowVisibilityModification() const
 {
   return m_AllowVisibilityModification;
 }
 
 void QmitkMultiLabelTreeModel::SetAllowLockModification(bool lmod)
 {
   m_AllowLockModification = lmod;
 }
 
 bool QmitkMultiLabelTreeModel::GetAllowLockModification() const
 {
   return m_AllowLockModification;
 }