diff --git a/src/application/xqappdata.h b/src/application/xqappdata.h
index 8c3c88d..0418eeb 100644
--- a/src/application/xqappdata.h
+++ b/src/application/xqappdata.h
@@ -38,6 +38,7 @@ const QString c_ProjectID          = "ProjectID";
 const QString c_ModelSheetFileName = "xml/modelsheets.xml";
 const QString c_ModelDummyFileName = "xml/saved_testfile.xtr";
 const QString c_DocumentDirectory  = "xml/";
+
 const QString c_DocumentFileName1  = "xml/modeldata1.xtr";
 const QString c_DocumentFileName2  = "xml/modeldata2.xtr";
 const QString c_DocumentFileName3  = "xml/modeldata3.xtr";
diff --git a/src/application/xqdocumentstore.cpp b/src/application/xqdocumentstore.cpp
index dd1ec5d..cf700f9 100644
--- a/src/application/xqdocumentstore.cpp
+++ b/src/application/xqdocumentstore.cpp
@@ -18,8 +18,8 @@
 
 //! erzeugt ein docukument
 
-XQDocument::XQDocument(const QString& aFileName, const QString& aFriendlyName, XQItem* aTreeItem, XQViewModel* aModelView )
-    : fileName{ aFileName }, friendlyName{ aFriendlyName }, treeItem{ aTreeItem }, modelView{ aModelView }
+XQDocument::XQDocument(const QString& aFileName, const QString& aFriendlyName, XQItem* aTreeItem, XQViewModel* aViewModel )
+    : fileName{ aFileName }, friendlyName{ aFriendlyName }, treeItem{ aTreeItem }, viewModel{ aViewModel }
 {
 
 }
@@ -44,9 +44,9 @@ XQDocumentStore::~XQDocumentStore()
 
 //! erzeugt ein document eintrag
 
-void XQDocumentStore::addDocument( const QString& aFileName, const QString& aFriendlyName, XQItem* aTreeItem, XQViewModel* aModelView )
+void XQDocumentStore::addDocument(const QString& aFileName, const QString& aFriendlyName, XQItem* aTreeItem, XQViewModel* aViewModel )
 {
-  XQDocument newDocument( aFileName, aFriendlyName, aTreeItem, aModelView );
+  XQDocument newDocument( aFileName, aFriendlyName, aTreeItem, aViewModel );
   addAtKey(  aFileName, newDocument );
   // attention: this assumes the presence of the 'ProjectID' value
   //addAlias( aFileName, aTreeItem->attribute(c_ProjectID) );
diff --git a/src/application/xqdocumentstore.h b/src/application/xqdocumentstore.h
index 0d789f2..9119ab8 100644
--- a/src/application/xqdocumentstore.h
+++ b/src/application/xqdocumentstore.h
@@ -28,12 +28,10 @@ struct XQDocument
   XQDocument() = default;
   XQDocument( const QString& aFileName, const QString& aFriendlyName, XQItem* aTreeItem, XQViewModel* aModelView );
 
-  virtual ~XQDocument() = default;
-
   QString      fileName; // also used as key
   QString      friendlyName;
   XQItem*      treeItem{};
-  XQViewModel* modelView{};
+  XQViewModel* viewModel{};
 
 };
 
@@ -46,11 +44,7 @@ public:
   XQDocumentStore() = default;
   virtual ~ XQDocumentStore();
 
-  void addDocument( const QString& aFileName, const QString& aFriendlyName, XQItem* aTreeItem, XQViewModel* aModelView );
-
-protected:
-
-  XQNode _treeRootNode{ "treeRootNode" };
+  void addDocument( const QString& aFileName, const QString& aFriendlyName, XQItem* aTreeItem, XQViewModel* aViewModel );
 
 };
 
diff --git a/src/application/xqmainwindow.cpp b/src/application/xqmainwindow.cpp
index ade4203..e85e928 100644
--- a/src/application/xqmainwindow.cpp
+++ b/src/application/xqmainwindow.cpp
@@ -98,7 +98,7 @@ void XQMainWindow::initMainWindow()
 
   connect( _mainTreeView, &QTreeView::clicked, this, [&,this](const QModelIndex& index)
   {
-    onChildViewItemClicked( XQItem::xqItemFromIndex(index) );
+    onTreeViewItemClicked( XQItem::xqItemFromIndex(index) );
   });
 
 
@@ -125,7 +125,8 @@ void XQMainWindow::initMainWindow()
 
     // #2. load demo data
     loadDocument( c_DocumentFileName1 );
-    loadDocumentQML( c_DocumentFileName2 );
+    //loadDocumentQML( c_DocumentFileName2 );
+    loadDocument( c_DocumentFileName2 );
 
     qDebug() << " --- all here: " << XQNode::s_Count;
 
@@ -259,48 +260,58 @@ void XQMainWindow::onAbout()
 
 void XQMainWindow::onTreeViewItemClicked( const XQItem& item )
 {
-
-  qDebug() << " --- XXX mainWindow onTreeItemClicked:" << item.text();
+  /*
   _mainTreeView->selectionModel()->select(item.index(), QItemSelectionModel::Select);
 
   if( XQNodePtr contentNode = item.contentNode() )
   {
-    //XQNodePtr contentNode = item.contentNode()
     QString key = contentNode->attribute(c_ProjectID);
-    qDebug() << " --- FIRZ: key: " << key;
-
     bool isThere = _documentStore.contains(key);
     if( isThere)
-      _tabWidget->setCurrentWidget( _documentStore[key].modelView->treeTable() );
+      _tabWidget->setCurrentWidget( _documentStore[key].viewModel->treeTable() );
+  }
+  */
+
+  qDebug() << " --- Tree item CLICK:"  << item.text() << " : " << item.itemType().text();
+  if( item.itemType().text() == "TreeChildType" )
+  {
+    setChildTabByName( item.text() );
   }
 }
 
-void XQMainWindow::onTreeViewItemChanged(const XQItem &item )
+void XQMainWindow::onTreeViewItemChanged(const XQItem& item )
 {
-  qDebug() << " --- MAIN WINDOW on itemChanged:"  << item.text();
-}
-
-void XQMainWindow::onChildViewItemClicked( const XQItem& item )
-{
-  qDebug() << " --- MAIN WINDOW on CHILD item CLICK:"  << item.text();
-}
-
-void XQMainWindow::onChildViewItemChanged(const XQItem &item )
-{
-    qDebug() << " --- MAIN WINDOW on CHILD itemChanged:"  << item.text();
+  qDebug() << " --- TREE VIEW itemChanged:" << item.text() << " : " << item.parent()->text();
+  // hier müssen wir erst das projekt aktivieren
+  XQItem* xqItem = static_cast<XQItem*>(item.parent());
+  onTreeViewItemClicked( *xqItem );
+  //if( item.itemType().text() == "TreeSectionType" )
+  {
+    int idx = _tabWidget->currentIndex();
+    if(_documentStore.contains(idx) )
+    {
+      qDebug() << " --- should toggle: " << item.text();
+      XQViewModel& childModel = *_documentStore[idx].viewModel;
+      childModel.toggleSection(item.text());
+    }
+  }
 }
 
 
 //! beim click auf ein tab im linken fenster wird der navigationsbaum angepasst.
 
-void XQMainWindow::onChildViewTabClicked( int index )
+void XQMainWindow::onChildViewTabClicked( int idx )
 {
-  qDebug() << " --- onChildTabClicked: "  << index;
-  //const QString& key = _documentStore[index].treeItem->attribute( c_ProjectID );
-  //qDebug() << " ---- tab clicked: " << index  << " : " << _documentStore[index].friendlyName;// << ": " << key;
-  //_mainTreeView->setCurrentIndex( _documentStore[index]->treeTtem.index() );
+  if(_documentStore.contains(idx) )
+  {
+    QModelIndex treeIndex =_documentStore[idx].treeItem->index();
+    _mainModel.expandNewItem( treeIndex );
+  }
 }
 
+
+//! firz
+
 void XQMainWindow::onSectionCreated( const XQModelSection& section )
 {
   qDebug() << " --- XXX section created: " << section.contentType() << ":" << section.sheetRootNode()->to_string();
@@ -315,16 +326,16 @@ void XQMainWindow::onSectionToggled( const XQModelSection& section )
   //qDebug() << " --- XXX section toggled: " << section.contentType() << ":" << section.sheetRootNode()->to_string();
 }
 
-QStandardItemModel* createModel() {
-  auto* model = new QStandardItemModel;
-  model->setHorizontalHeaderLabels({ "Name" });
-
-  QStandardItem* parent = new QStandardItem("Tiere");
-  parent->appendRow(new QStandardItem("Hund"));
-  parent->appendRow(new QStandardItem("Katze"));
-  model->appendRow(parent);
-
-  return model;
+void XQMainWindow::setChildTabByName( const QString& key )
+{
+  for( int i=0; i<_documentStore.size(); ++i )
+  {
+    if( key ==  _documentStore[i].friendlyName)
+    {
+      _tabWidget->setCurrentIndex(i);
+      return;
+    }
+  }
 }
 
 void XQMainWindow::loadDocumentQML( const QString& fileName )
@@ -391,13 +402,13 @@ void XQMainWindow::loadDocument( const QString& fileName )
   // 'friendly Name' ist ein Link auf ein anderes Attribute
   // das als Namen verwendet wird.
   const QString& fName = contentRoot->friendly_name();
-  QString pTitle = QString("Project %1: %2").arg( pID, fName );
+  QString pTabTitle = QString("Project %1: %2").arg( pID, fName );
 
   // Eine neue TreeView erzeugn und im TabWidget parken.
   XQTreeTable* childTreeView = new XQTreeTable(_tabWidget);
-  _tabWidget->addTab( childTreeView, pTitle );
+  _tabWidget->addTab( childTreeView, pTabTitle );
   _tabWidget->setCurrentWidget( childTreeView );
-  setWindowTitle( pTitle );
+  setWindowTitle( pTabTitle );
 
   // Ein neues Child-Model erzeugen
   XQChildModel* childModel = new XQChildModel(this);
@@ -413,7 +424,7 @@ void XQMainWindow::loadDocument( const QString& fileName )
 
   // neuen eintrag im übsichts-baum erzeugen
   _currentProjectItem = _mainModel.addProjectItem( contentRoot );
-  _documentStore.addDocument( fileName, pTitle, _currentProjectItem, childModel );
+  _documentStore.addDocument( fileName, fName, _currentProjectItem, childModel );
 
   // die Modelstruktur anlegen
   childModel->initModel( c_ChildModelName );
@@ -432,7 +443,7 @@ void XQMainWindow::saveDocument( const QString& fileName )
   XQNodeWriter nodeWriter;
   int curIdx = _tabWidget->currentIndex();
   //XQNodePtr rootNode = _documentStore[curIdx].treeItem->contentNode();
-  XQNodePtr rootNode = _documentStore[curIdx].modelView->contentRootNode();
+  XQNodePtr rootNode = _documentStore[curIdx].viewModel->contentRootNode();
   Q_ASSERT(rootNode);
   nodeWriter.dumpTree( rootNode, fileName );
 }
diff --git a/src/application/xqmainwindow.h b/src/application/xqmainwindow.h
index 1fbfbb9..b4d172d 100644
--- a/src/application/xqmainwindow.h
+++ b/src/application/xqmainwindow.h
@@ -51,33 +51,32 @@ public slots:
   void onAbout();
   void onExit();
 
-  void onTreeViewItemClicked(const XQItem& item );
+  void onTreeViewItemClicked( const XQItem& item );
   void onTreeViewItemChanged( const XQItem& item );
-  void onChildViewItemClicked( const XQItem& item );
-  void onChildViewItemChanged( const XQItem& item );
   void onChildViewTabClicked( int index );
 
   //void onItemCreated( XQItem* item );
   void onSectionCreated( const XQModelSection& section);
   void onSectionToggled( const XQModelSection& section );
 
+  void setChildTabByName( const QString& key );
+
   static void setupWorkingDir();
 
 protected:
 
   // fixme implement
-  void showDocumnet( const QString& key ){}
+  void showDocument( const QString& key ){}
   void loadDocument( const QString& fileName );
   void loadDocumentQML( const QString& fileName );
   void saveDocument( const QString& fileName );
 
-
   QUndoStack      _undoStack;
   XQDocumentStore _documentStore;
 
   XQMainModel     _mainModel;
   XQItem*         _currentProjectItem{};
-
+  //XQChildModel*   _currentChildModel{};
 
 };
 
diff --git a/src/model/xqviewmodel.cpp b/src/model/xqviewmodel.cpp
index abea403..38f5d74 100644
--- a/src/model/xqviewmodel.cpp
+++ b/src/model/xqviewmodel.cpp
@@ -199,7 +199,11 @@ void XQViewModel::toggleSection( const XQModelSection& section )
 
 void XQViewModel::toggleSection( const QString& sectionKey )
 {
-
+  if( _sections.hasValidSection( sectionKey ) )
+  {
+    XQModelSection& section = _sections.at( sectionKey);
+    //section.
+  }
 }
 
 /*
diff --git a/src/util/xqmaptor.h b/src/util/xqmaptor.h
index 5435868..9aa6c60 100644
--- a/src/util/xqmaptor.h
+++ b/src/util/xqmaptor.h
@@ -73,6 +73,16 @@ public:
     return _data.end();
   }
 
+  auto begin() const
+  {
+    return _data.begin();
+  }
+
+  auto end() const
+  {
+    return _data.end();
+  }
+
   inline int size() const
   {
     return (int) _data.size();
@@ -94,13 +104,11 @@ public:
     return mapIndex().contains(key);
   }
 
- 
   inline const XQMapIndex& mapIndex() const
   {
     return _index;
   }
 
-
   int indexOf( const QString& key ) const
   {   
     return mapIndex().indexOf(key);
@@ -121,7 +129,6 @@ public:
     return mapIndex().key( index );
   }
 
-
   T& operator[]( int index )
   {
     if( contains(index) )
@@ -129,7 +136,6 @@ public:
     throw XQException("XQMaptor operator[ int index ]: out of range");
   }
 
-
   const T& operator[]( int index ) const
   {
     if ( contains(index) )
@@ -154,7 +160,6 @@ public:
     return _data[ _index[key] ];
   }
 
-
   const T& operator[]( const QString& key ) const
   {
     if (key.isEmpty() || !contains(key))
@@ -162,7 +167,6 @@ public:
     return _data[_index[key]];
   }
 
-
   T& at( const QString& key )
   {
     return (*this)[key];
@@ -179,7 +183,6 @@ public:
     return _data.size()-1;
   }
 
-
   virtual void addAtIndex( int index, const T& item  )
   {
     if(contains(index))
@@ -187,14 +190,12 @@ public:
     _data[index] = item;
   }
 
-
   // convenience method to mimic QMap<T,QString>
   virtual void insert( const T& item, const QString& key )
   {
     addAtKey(key, item );
   }
 
-
   virtual void addAtKey( const QString& key, const T& item )
   {
     XQMapIndex::iterator pos = _index.find( key );
@@ -209,7 +210,6 @@ public:
     }
   }
 
-
   bool addAlias( const QString& key, const QString& alias )
   {
     // look for 'original' key
@@ -227,20 +227,17 @@ public:
     return true;
   }
 
-
   void addKey( const QString& key, int index )
   {
     _index.addKey( key, index );
   }
 
-
   virtual void clear()
   {
     _data.clear();
     _index.clear();
   }
 
-
   virtual bool killEntry( const QString& key )
   {
     int idx = indexOf( key );
@@ -249,7 +246,6 @@ public:
     return killEntry( (int) idx );
   }
 
-
   virtual bool killEntry( int index )
   {
     if( index >= this->_data.size() )
@@ -261,19 +257,16 @@ public:
     return true;
   }
 
-
   virtual QString toString() const
   {
     return join( ";" );
   }
 
-
   virtual void dump() const
   {
     throw XQException("XQMaptor: dump not implemented!" );
   }
 
-
   virtual QString join( const QString& sep, int from=0, int to=-1) const
   {
     Q_UNUSED(sep)
@@ -283,7 +276,6 @@ public:
     return "--";
   }
 
-
   int replaceKey( const QString& oldkey, const QString& newkey )
   {
     int idx = indexOf( oldkey );