diff --git a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementDemoTab.h b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementDemoTab.h
index 9d4f78786ac..7117df439e3 100644
--- a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementDemoTab.h
+++ b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementDemoTab.h
@@ -62,10 +62,11 @@ public:
     typedef ArrangementDemoTabBase Superclass;
     typedef Arr_ Arrangement;
 
-    ArrangementDemoTab( Arrangement* arrangement_, QWidget* parent ):
+    ArrangementDemoTab( Arrangement* arrangement_, QWidget* parent = 0 ):
         Superclass( parent ),
         arrangement( arrangement_ )
     {
+        std::cout << this->scene->views( ).size( ) << std::endl;
         // set up demo components
         this->arrangementGraphicsItem = new CGAL::Qt::ArrangementGraphicsItem< Arrangement >( this->arrangement );
         this->curveInputCallback = new ArrangementCurveInputCallback< Arrangement >( this->arrangement, this );
diff --git a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementDemoWindow.cpp b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementDemoWindow.cpp
index 52ec2684fd7..b42622a6a83 100644
--- a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementDemoWindow.cpp
+++ b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementDemoWindow.cpp
@@ -15,7 +15,6 @@
 #include <CGAL/IO/Arr_text_formatter.h>
 #include <CGAL/IO/Arr_with_history_text_formatter.h>
 
-
 ArrangementDemoWindow::
 ArrangementDemoWindow(QWidget* parent) :
     CGAL::Qt::DemosMainWindow( parent ),
@@ -57,6 +56,7 @@ makeTab( TraitsType tt )
     Seg_arr* seg_arr;
     Pol_arr* pol_arr;
     Conic_arr* conic_arr;
+    Lin_arr* lin_arr;
     CGAL::Object arr;
 
     switch ( tt )
@@ -80,6 +80,12 @@ makeTab( TraitsType tt )
         arr = CGAL::make_object( conic_arr );
         tabLabel = QString( "%1 - Conic" ).arg( tabLabelCounter++ );
         break;
+    case LINEAR_TRAITS:
+        lin_arr = new Lin_arr;
+        demoTab = new ArrangementDemoTab< Lin_arr >( lin_arr, 0 );
+        arr = CGAL::make_object( lin_arr );
+        tabLabel = QString( "%1 - Linear" ).arg( tabLabelCounter++ );
+        break;
     }
 
     this->arrangements.push_back( arr );
@@ -177,6 +183,8 @@ setupUi( )
     this->conicTypeGroup->addAction( this->ui->actionConicEllipse );
     this->conicTypeGroup->addAction( this->ui->actionConicThreePoint );
     this->conicTypeGroup->addAction( this->ui->actionConicFivePoint );
+    this->conicTypeGroup->addAction( this->ui->actionCurveRay );
+    this->conicTypeGroup->addAction( this->ui->actionCurveLine );
 }
 
 void
@@ -394,7 +402,9 @@ updateConicType( QAction* newType )
     QGraphicsScene* activeScene = activeTab->getScene( );
     ArrangementDemoGraphicsView* activeView = activeTab->getView( );
     Conic_arr* conic_arr;
+    Lin_arr* lin_arr;
     bool isConicArr = CGAL::assign( conic_arr, this->arrangements[ this->ui->tabWidget->currentIndex( ) ] );
+    bool isLinearArr = CGAL::assign( lin_arr, this->arrangements[ this->ui->tabWidget->currentIndex( ) ] );
     if ( isConicArr )
     {
         std::cout << "do something conic arr related" << std::endl;
@@ -421,8 +431,22 @@ updateConicType( QAction* newType )
             curveInputCallback->setConicType( ConicCurveInputCallback::CONIC_FIVE_POINT );
         }
     }
-    else
+    else if ( isLinearArr )
     {
+        typedef CGAL::Qt::GraphicsViewCurveInput< typename Lin_arr::Geometry_traits_2 > LinearCurveInputCallback;
+        LinearCurveInputCallback* curveInputCallback = ( LinearCurveInputCallback* ) activeTab->getCurveInputCallback( );
+        if ( newType == this->ui->actionConicSegment )
+        {
+            curveInputCallback->setCurveType( LinearCurveInputCallback::SEGMENT );
+        }
+        else if ( newType == this->ui->actionCurveRay )
+        {
+            curveInputCallback->setCurveType( LinearCurveInputCallback::RAY );
+        }
+        else if ( newType == this->ui->actionCurveLine )
+        {
+            curveInputCallback->setCurveType( LinearCurveInputCallback::LINE );
+        }
         //std::cout << "do nothing" << std::endl;
     }
 }
@@ -614,6 +638,10 @@ on_actionNewTab_triggered( )
         {
             this->makeTab( CONIC_TRAITS );
         }
+        else if ( id == LINEAR_TRAITS )
+        {
+            this->makeTab( LINEAR_TRAITS );
+        }
         else
         {
             std::cout << "Sorry, this trait is not yet supported" << std::endl;
@@ -637,16 +665,52 @@ on_tabWidget_currentChanged( )
     CGAL::Object arr;
     if ( this->ui->tabWidget->currentIndex( ) != -1 )
         arr = this->arrangements[ this->ui->tabWidget->currentIndex( ) ];
+
     Seg_arr* seg;
     Pol_arr* pol;
     Conic_arr* conic;
+    Lin_arr* lin;
     if ( CGAL::assign( conic, arr ) )
     {
+        this->ui->actionConicSegment->setChecked( true );
+
+        this->ui->actionCurveRay->setVisible( false );
+        this->ui->actionCurveLine->setVisible( false );
+
+        this->ui->actionConicCircle->setVisible( true );
+        this->ui->actionConicEllipse->setVisible( true );
+        this->ui->actionConicThreePoint->setVisible( true );
+        this->ui->actionConicFivePoint->setVisible( true );
+
+        this->conicTypeGroup->setEnabled( true );
+    }
+    else if ( CGAL::assign( lin, arr ) )
+    {
+        this->ui->actionConicSegment->setChecked( true );
+
+        this->ui->actionCurveRay->setVisible( true );
+        this->ui->actionCurveLine->setVisible( true );
+
+        this->ui->actionConicCircle->setVisible( false );
+        this->ui->actionConicEllipse->setVisible( false );
+        this->ui->actionConicThreePoint->setVisible( false );
+        this->ui->actionConicFivePoint->setVisible( false );
+
         this->conicTypeGroup->setEnabled( true );
     }
     else
-    {
-        this->conicTypeGroup->setEnabled( false );
+    { // segment or polyline
+        this->ui->actionConicSegment->setChecked( true );
+
+        this->ui->actionCurveRay->setVisible( false );
+        this->ui->actionCurveLine->setVisible( false );
+
+        this->ui->actionConicCircle->setVisible( false );
+        this->ui->actionConicEllipse->setVisible( false );
+        this->ui->actionConicThreePoint->setVisible( false );
+        this->ui->actionConicFivePoint->setVisible( false );
+
+        this->conicTypeGroup->setEnabled( true );
     }
 }
 
diff --git a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementDemoWindow.h b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementDemoWindow.h
index 8a13e76a725..927c037d858 100644
--- a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementDemoWindow.h
+++ b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementDemoWindow.h
@@ -43,7 +43,8 @@ public:
     typedef enum TraitsType {
         SEGMENT_TRAITS,
         POLYLINE_TRAITS,
-        CONIC_TRAITS
+        CONIC_TRAITS,
+        LINEAR_TRAITS
     } TraitsType;
     
     ArrangementDemoWindow(QWidget* parent = 0);
diff --git a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementDemoWindow.qrc b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementDemoWindow.qrc
index 0d2dfb176ac..088355f9a3b 100644
--- a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementDemoWindow.qrc
+++ b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementDemoWindow.qrc
@@ -1,5 +1,6 @@
 <RCC>
   <qresource>
+    <file>icons/demo_conic_line.xpm</file>
     <file>icons/demo_zoomin.xpm</file>
     <file>icons/demo_zoomout.xpm</file>
     <file>icons/yellow_icon.xpm</file>
@@ -11,6 +12,7 @@
     <file>icons/demo_conic_segment.xpm</file>
     <file>icons/demo_conic_3points.xpm</file>
     <file>icons/demo_snapvertex.xpm</file>
+    <file>icons/demo_conic_ray.xpm</file>
     <file>icons/lower_env_xpm.xpm</file>
     <file>icons/upper_env_xpm.xpm</file>
     <file>icons/demo_snapgrid.xpm</file>
diff --git a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementDemoWindow.ui b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementDemoWindow.ui
index 478f93a966e..6ccba51ad22 100644
--- a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementDemoWindow.ui
+++ b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementDemoWindow.ui
@@ -6,7 +6,7 @@
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>800</width>
+    <width>829</width>
     <height>600</height>
    </rect>
   </property>
@@ -29,7 +29,7 @@
     <rect>
      <x>0</x>
      <y>0</y>
-     <width>800</width>
+     <width>829</width>
      <height>25</height>
     </rect>
    </property>
@@ -127,6 +127,8 @@
    <addaction name="actionUpperEnvelope"/>
    <addaction name="separator"/>
    <addaction name="actionConicSegment"/>
+   <addaction name="actionCurveRay"/>
+   <addaction name="actionCurveLine"/>
    <addaction name="actionConicCircle"/>
    <addaction name="actionConicEllipse"/>
    <addaction name="actionConicThreePoint"/>
@@ -437,6 +439,30 @@
     <string>Zoom Out</string>
    </property>
   </action>
+  <action name="actionCurveRay">
+   <property name="checkable">
+    <bool>true</bool>
+   </property>
+   <property name="icon">
+    <iconset resource="ArrangementDemoWindow.qrc">
+     <normaloff>:/icons/demo_conic_ray.xpm</normaloff>:/icons/demo_conic_ray.xpm</iconset>
+   </property>
+   <property name="text">
+    <string>Ray</string>
+   </property>
+  </action>
+  <action name="actionCurveLine">
+   <property name="checkable">
+    <bool>true</bool>
+   </property>
+   <property name="icon">
+    <iconset resource="ArrangementDemoWindow.qrc">
+     <normaloff>:/icons/demo_conic_line.xpm</normaloff>:/icons/demo_conic_line.xpm</iconset>
+   </property>
+   <property name="text">
+    <string>Line</string>
+   </property>
+  </action>
  </widget>
  <resources>
   <include location="ArrangementDemoWindow.qrc"/>
diff --git a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementGraphicsItem.cpp b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementGraphicsItem.cpp
index ec05d6e912c..284305296fe 100644
--- a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementGraphicsItem.cpp
+++ b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementGraphicsItem.cpp
@@ -83,5 +83,23 @@ setScene( QGraphicsScene* scene_ )
     this->scene = scene_;
 }
 
+QRectF
+ArrangementGraphicsItemBase::
+getViewportRect( ) const
+{
+    QRectF clipRect;
+    if ( this->scene == NULL || this->scene->views( ).size( ) == 0 )
+    {
+        return clipRect;
+    }
+
+    QGraphicsView* view = this->scene->views( ).first( );
+    QPointF p1 = view->mapToScene( 0, 0 );
+    QPointF p2 = view->mapToScene( view->width( ), view->height( ) );
+    clipRect = QRectF( p1, p2 );
+
+    return clipRect;
+}
+
 } // namespace Qt
 } // namespace CGAL
diff --git a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementGraphicsItem.h b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementGraphicsItem.h
index 5c67fdeabb2..f500baadfad 100644
--- a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementGraphicsItem.h
+++ b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementGraphicsItem.h
@@ -51,6 +51,8 @@ public:
     void setScene( QGraphicsScene* scene_ );
 
 protected:
+    QRectF getViewportRect( ) const;
+
     CGAL::Bbox_2 bb;
     bool bb_initialized;
 
@@ -63,7 +65,7 @@ protected:
 
 }; // class ArrangementGraphicsItemBase
 
-template < class Arr_ >
+template < class Arr_, class ArrTraits = typename Arr_::Geometry_traits_2 >
 class ArrangementGraphicsItem : public ArrangementGraphicsItemBase
 {
     typedef Arr_ Arrangement;
@@ -78,10 +80,9 @@ class ArrangementGraphicsItem : public ArrangementGraphicsItemBase
 
 public:
     ArrangementGraphicsItem( Arrangement* t_ );
-    void modelChanged( );
 
 public:
-    // QGraphicsItem overrides
+    void modelChanged( );
     QRectF boundingRect( ) const;
     virtual void paint( QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget );
 
@@ -95,8 +96,8 @@ protected:
     std::map< Curve_iterator, CGAL::Bbox_2 > curveBboxMap;
 }; // class ArrangementGraphicsItem
 
-template < class Arr_ >
-ArrangementGraphicsItem< Arr_ >::
+template < class Arr_, class ArrTraits >
+ArrangementGraphicsItem< Arr_, ArrTraits >::
 ArrangementGraphicsItem( Arrangement* arr_ ):
     arr( arr_ ),
     painterostream( 0 )
@@ -108,32 +109,22 @@ ArrangementGraphicsItem( Arrangement* arr_ ):
     this->setZValue( 3 );
 }
 
-template < class Arr_ >
+template < class Arr_, class ArrTraits >
 QRectF 
-ArrangementGraphicsItem< Arr_ >::
+ArrangementGraphicsItem< Arr_, ArrTraits >::
 boundingRect( ) const
 {
     QRectF rect = this->convert( this->bb );
     return rect;
 }
 
-template < class Arr_ >
+template < class Arr_, class ArrTraits >
 void 
-ArrangementGraphicsItem< Arr_ >::paint(QPainter *painter, 
+ArrangementGraphicsItem< Arr_, ArrTraits >::paint(QPainter *painter, 
                                     const QStyleOptionGraphicsItem *option,
                                     QWidget * /*widget*/)
 {
-    //painter->setClipping( true );
-    //painter->drawRect( this->boundingRect( ) );
 
-#if 0
-    QTransform transform = painter->worldTransform( );
-    if ( transform.isScaling( ) )
-    {
-        std::cout << "Cool, we're scaling." << std::endl;
-        std::cout << transform.m11( ) << std::endl;
-    }
-#endif
     painter->setPen( this->verticesPen );
     this->painterostream = ArrangementPainterOstream< Traits >( painter, this->boundingRect( ) );
     this->painterostream.setScene( this->scene );
@@ -146,12 +137,6 @@ ArrangementGraphicsItem< Arr_ >::paint(QPainter *painter,
     painter->setPen( this->edgesPen );
     for ( Edge_iterator it = this->arr->edges_begin( ); it != this->arr->edges_end( ); ++it )
     {
-#if 0
-        Point_2 p1 = it->source( )->point( );
-        Point_2 p2 = it->target( )->point( );
-        Segment_2 edge( p1, p2 );
-        this->painterostream << edge;
-#endif
         X_monotone_curve_2 curve = it->curve( );
         this->painterostream << curve;
     }
@@ -159,9 +144,9 @@ ArrangementGraphicsItem< Arr_ >::paint(QPainter *painter,
 
 // We let the bounding box only grow, so that when vertices get removed
 // the maximal bbox gets refreshed in the GraphicsView
-template < class Arr_ >
+template < class Arr_, class ArrTraits >
 void 
-ArrangementGraphicsItem< Arr_ >::updateBoundingBox( )
+ArrangementGraphicsItem< Arr_, ArrTraits >::updateBoundingBox( )
 {
     this->prepareGeometryChange( );
     if ( this->arr->number_of_vertices( ) == 0 )
@@ -188,9 +173,9 @@ ArrangementGraphicsItem< Arr_ >::updateBoundingBox( )
     }
 }
 
-template < class Arr_ >
+template < class Arr_, class ArrTraits >
 void 
-ArrangementGraphicsItem< Arr_ >::modelChanged( )
+ArrangementGraphicsItem< Arr_, ArrTraits >::modelChanged( )
 {
     if ( this->arr->is_empty( ) )
     {
@@ -204,6 +189,129 @@ ArrangementGraphicsItem< Arr_ >::modelChanged( )
     this->update( );
 }
 
+/**
+ * Why is this not being used?
+Specialized methods:
+    updateBoundingBox
+*/
+template < class Arr_, class Kernel_ >
+class ArrangementGraphicsItem< Arr_, CGAL::Arr_linear_traits_2< Kernel_ > >  : public ArrangementGraphicsItemBase
+{
+    typedef Arr_ Arrangement;
+    typedef ArrangementGraphicsItemBase Superclass;
+    typedef typename Arrangement::Geometry_traits_2 Traits;
+    typedef typename Arrangement::Vertex_iterator Vertex_iterator;
+    typedef typename Arrangement::Curve_iterator Curve_iterator;
+    typedef typename Arrangement::Edge_iterator Edge_iterator;
+    typedef typename ArrTraitsAdaptor< Traits >::Kernel Kernel;
+    typedef typename Traits::X_monotone_curve_2 X_monotone_curve_2;
+    typedef typename Kernel::Point_2 Point_2;
+    typedef typename Kernel::Segment_2 Segment_2;
+
+public:
+    ArrangementGraphicsItem( Arrangement* arr_ ):
+        arr( arr_ ),
+        painterostream( 0 )
+    {
+        if ( this->arr->number_of_vertices( ) == 0 ) {
+            this->hide( );
+        }
+        this->updateBoundingBox( );
+        this->setZValue( 3 );
+    }
+
+    void modelChanged( )
+    {
+        if ( this->arr->is_empty( ) )
+        {
+            this->hide( );
+        }
+        else
+        {
+            this->show( );
+        }
+        this->updateBoundingBox( );
+        this->update( );
+    }
+
+
+public: // methods
+    // @override QGraphicsItem::boundingRect
+    QRectF boundingRect( ) const
+    {
+        QRectF rect = this->convert( this->bb );
+        return rect;
+    }
+
+    // @override QGraphicsItem::paint
+    virtual void paint( QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget )
+    {
+        this->updateBoundingBox( );
+        painter->setPen( this->verticesPen );
+        this->painterostream = ArrangementPainterOstream< Traits >( painter, this->boundingRect( ) );
+        this->painterostream.setScene( this->scene );
+
+        for ( Vertex_iterator it = this->arr->vertices_begin( ); it != this->arr->vertices_end( ); ++it )
+        {
+            Point_2 pt = it->point( );
+            this->painterostream << pt;
+        }
+        painter->setPen( this->edgesPen );
+        for ( Edge_iterator it = this->arr->edges_begin( ); it != this->arr->edges_end( ); ++it )
+        {
+            X_monotone_curve_2 curve = it->curve( );
+            this->painterostream << curve;
+        }
+    }
+
+protected: // methods
+    void updateBoundingBox( )
+    {
+        this->prepareGeometryChange( );
+        QRectF clipRect = this->getViewportRect( );
+        this->convert = Converter<Kernel>( clipRect );
+
+        if ( ! clipRect.isValid( ) /*|| this->arr->number_of_vertices( ) == 0*/ )
+        {
+            this->bb = Bbox_2( 0, 0, 0, 0 );
+            this->bb_initialized = false;
+            return;
+        }
+        else
+        {
+            this->bb = this->convert( clipRect ).bbox( );
+            this->bb_initialized = true;
+        }
+
+        for ( Curve_iterator it = this->arr->curves_begin( );
+            it != this->arr->curves_end( );
+            ++it )
+        {
+            if ( it->is_segment( ) )
+            {
+                this->bb = this->bb + it->segment( ).bbox( );
+            }
+            else if ( it->is_ray( ) )
+            {
+                QLineF qclippedRay = this->convert( it->ray( ) );
+                Segment_2 clippedRay = this->convert( qclippedRay );
+                this->bb = this->bb + clippedRay.bbox( );
+            }
+            else // ( it->is_line( ) )
+            {
+                QLineF qclippedLine = this->convert( it->line( ) );
+                Segment_2 clippedLine = this->convert( qclippedLine );
+                this->bb = this->bb + clippedLine.bbox( );
+            }
+        }
+    }
+
+protected: // fields
+    Arrangement* arr;
+    ArrangementPainterOstream< Traits > painterostream;
+    CGAL::Qt::Converter< Kernel > convert;
+}; // class ArrangementGraphicsItem
+
 } // namespace Qt
 } // namespace CGAL
 
diff --git a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementPainterOstream.h b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementPainterOstream.h
index 4bef673b1a5..2beba1d2203 100644
--- a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementPainterOstream.h
+++ b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementPainterOstream.h
@@ -8,6 +8,7 @@
 #include <CGAL/Arr_segment_traits_2.h>
 #include <CGAL/Arr_polyline_traits_2.h>
 #include <CGAL/Arr_conic_traits_2.h>
+#include <CGAL/Arr_linear_traits_2.h>
 
 #include "Utils.h"
 #include <vector>
@@ -74,18 +75,6 @@ protected: // methods
         QPointF p1 = view->mapToScene( 0, 0 );
         QPointF p2 = view->mapToScene( view->width( ), view->height( ) );
         QRectF clipRect = QRectF( p1, p2 );
-#if 0
-        std::cout << "("
-            << p1.x( )
-            << " "
-            << p1.y( )
-            << " "
-            << p2.x( )
-            << " "
-            << p2.y( )
-            << ")"
-            << std::endl;
-#endif
 
         return clipRect;
     }
@@ -608,6 +597,101 @@ protected: // members
     Construct_x_monotone_curve_2 construct_x_monotone_curve_2;
 };
 
+template < class Kernel_ >
+class ArrangementPainterOstream< CGAL::Arr_linear_traits_2< Kernel_ > >:
+    public ArrangementPainterOstreamBase< CGAL::Arr_linear_traits_2< Kernel_ > >
+{
+public: // typedefs
+    typedef Kernel_ Kernel;
+    typedef CGAL::Arr_linear_traits_2< Kernel > Traits;
+    typedef ArrangementPainterOstreamBase< Traits > Superclass;
+    typedef typename Superclass::Point_2 Point_2;
+    typedef typename Superclass::Segment_2 Segment_2;
+    typedef typename Superclass::Ray_2 Ray_2;
+    typedef typename Superclass::Line_2 Line_2;
+    typedef typename Superclass::Triangle_2 Triangle_2;
+    typedef typename Superclass::Iso_rectangle_2 Iso_rectangle_2;
+    typedef typename Superclass::Circle_2 Circle_2;
+    typedef typename Traits::Curve_2 Curve_2;
+    typedef typename Traits::X_monotone_curve_2 X_monotone_curve_2;
+
+public: // constructors
+    ArrangementPainterOstream( QPainter* p, QRectF clippingRectangle = QRectF( ) ):
+        Superclass( p, clippingRectangle )
+    { }
+
+public: // methods
+    ArrangementPainterOstream& operator<<( const X_monotone_curve_2& curve )
+    {
+        if ( curve.is_segment( ) )
+        {
+            Segment_2 seg = curve.segment( );
+
+            // skip segments outside our view
+            QRectF seg_bb = this->convert( seg.bbox( ) );
+            if ( this->clippingRect.isValid( ) &&
+                ! this->clippingRect.intersects( seg_bb ) )
+            {
+                return *this;
+            }
+
+            this->painterOstream << seg;
+        }
+        else if ( curve.is_ray( ) )
+        {
+            Ray_2 ray = curve.ray( );
+            QLineF qseg = this->convert( ray );
+            if ( qseg.isNull( ) )
+            { // it's out of view
+                return *this;
+            }
+            Segment_2 seg = this->convert( qseg );
+            this-> painterOstream << seg;
+        }
+        else // curve.is_line( )
+        {
+            Line_2 line = curve.line( );
+            QLineF qseg = this->convert( line );
+            if ( qseg.isNull( ) )
+            { // it's out of view
+                return *this;
+            }
+            Segment_2 seg = this->convert( qseg );
+            this-> painterOstream << seg;
+        }
+        return *this;
+    }
+
+    ArrangementPainterOstream& operator<<( const Point_2& p )
+    {
+        QPointF qpt = this->convert( p );
+        // clip the point if possible
+        if ( this->clippingRect.isValid( ) &&
+            ! this->clippingRect.contains( qpt ) )
+        {
+            return *this;
+        }
+
+        QPen savePen = this->qp->pen( );
+        this->qp->setBrush( QBrush( savePen.color( ) ) );
+        double radius = savePen.width( ) / 2.0;
+        radius /= this->scale;
+
+        this->qp->drawEllipse( qpt, radius, radius );
+
+        this->qp->setBrush( QBrush( ) );
+        this->qp->setPen( savePen );
+        return *this;
+    }
+
+    template < class T >
+    ArrangementPainterOstream& operator<<( const T& p )
+    {
+        (*(static_cast< Superclass* >(this)) << p);
+        return *this;
+    }
+};
+
 } // namespace Qt
 } // namespace CGAL
 #endif // CGAL_QT_ARRANGEMENT_PAINTER_OSTREAM_H
diff --git a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementTypes.h b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementTypes.h
index 36398ad26ce..f18eaedc687 100644
--- a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementTypes.h
+++ b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementTypes.h
@@ -33,6 +33,7 @@
 #include <CGAL/Cartesian.h>
 #include <CGAL/Arr_default_dcel.h>
 #include <CGAL/Arr_segment_traits_2.h>
+#include <CGAL/Arr_linear_traits_2.h>
 #include <CGAL/Arr_consolidated_curve_data_traits_2.h>
 #include <CGAL/Arr_polyline_traits_2.h>
 #include <CGAL/Arrangement_with_history_2.h>
@@ -238,6 +239,35 @@ typedef CGAL::Arr_landmarks_point_location<Conic_arr>
 
 #endif
 
+// Linear:
+typedef CGAL::Arr_linear_traits_2<Kernel>               Lin_traits;
+typedef Lin_traits::Curve_2                             Arr_lin_2;
+typedef Lin_traits::X_monotone_curve_2                  Arr_xlin_2;
+typedef Lin_traits::Point_2                             Arr_lin_point_2;
+typedef Dcel<Lin_traits>                                Lin_dcel;
+typedef CGAL::Arrangement_with_history_2<Lin_traits,
+                                         Lin_dcel>      Lin_arr;
+typedef Lin_arr::Halfedge                               Lin_halfedge;
+typedef Lin_arr::Halfedge_handle                        Lin_halfedge_handle;
+typedef Lin_arr::Face_handle                            Lin_face_handle;
+typedef Lin_arr::Ccb_halfedge_circulator                Lin_ccb_halfedge_circulator;
+typedef Lin_arr::Hole_iterator                          Lin_holes_iterator;
+typedef Lin_arr::Face_iterator                          Lin_face_iterator;
+typedef std::list<Arr_lin_2*>                           Arr_lin_list;
+typedef Arr_lin_list::const_iterator                    Arr_lin_const_iter;
+typedef Arr_lin_list::iterator                          Arr_lin_iter;
+
+//point location
+typedef CGAL::Arr_trapezoid_ric_point_location<Lin_arr>
+  Lin_trap_point_location;
+typedef CGAL::Arr_simple_point_location<Lin_arr>
+  Lin_simple_point_location;
+typedef CGAL::Arr_walk_along_line_point_location<Lin_arr>
+  Lin_walk_point_location;
+typedef CGAL::Arr_landmarks_point_location<Lin_arr>
+  Lin_landmarks_point_location;
+
+
 
 
 template <class Arrangement_>
diff --git a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/CurveGraphicsItem.h b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/CurveGraphicsItem.h
index 5a22d80f073..01edf827b28 100644
--- a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/CurveGraphicsItem.h
+++ b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/CurveGraphicsItem.h
@@ -3,6 +3,8 @@
 #include "ArrangementPainterOstream.h"
 #include <CGAL/Qt/Converter.h>
 #include <CGAL/Qt/GraphicsItem.h>
+#include <QGraphicsScene>
+
 namespace CGAL {
 namespace Qt {
 
@@ -16,23 +18,30 @@ public:
     typedef typename Traits::Curve_2 Curve_2;
     typedef typename Traits::X_monotone_curve_2 X_monotone_curve_2;
 
+public: // ctors
     CurveGraphicsItem( );
 
+public: // methods
     virtual void paint( QPainter* painter, const QStyleOptionGraphicsItem* option, QWidget* widget );
-    void updateBoundingBox( );
+    virtual QRectF boundingRect( ) const;
     void insert( const X_monotone_curve_2& curve );
     void clear( );
-    QRectF boundingRect( ) const;
+    void setScene( QGraphicsScene* scene_ );
 
 public slots:
     void modelChanged( );
 
-protected:
+protected: // methods
+    void updateBoundingBox( );
+    QRectF viewportRect( ) const;
+
+protected: // fields
     CGAL::Qt::Converter< Kernel > convert;
-    ArrangementPainterOstream< ArrTraits > painterOstream;
+    ArrangementPainterOstream< Traits > painterOstream;
     std::vector< X_monotone_curve_2 > curves;
     CGAL::Bbox_2 boundingBox;  
     bool boundingBoxInitialized;
+    QGraphicsScene* scene;
 }; // class CurveGraphicsItem
 
 template < class ArrTraits >
@@ -40,7 +49,8 @@ CurveGraphicsItem< ArrTraits >::
 CurveGraphicsItem( ):
     painterOstream( 0 ),
     boundingBox( 0, 0, 0, 0 ),
-    boundingBoxInitialized( false )
+    boundingBoxInitialized( false ),
+    scene( 0 )
 {
     this->setZValue( 4 );
 }
@@ -51,7 +61,8 @@ CurveGraphicsItem< ArrTraits >::
 paint( QPainter* painter, const QStyleOptionGraphicsItem* option, QWidget* widget )
 {
     painter->setPen( QPen( ::Qt::red, 0. ) );
-    this->painterOstream = ArrangementPainterOstream< ArrTraits >( painter/*, clippingRectangle */ );
+    QRectF clippingRectangle = this->viewportRect( );
+    this->painterOstream = ArrangementPainterOstream< Traits >( painter, clippingRectangle );
     for ( int i = 0; i < this->curves.size( ); ++i )
     {
         X_monotone_curve_2 curve = this->curves[ i ];
@@ -59,6 +70,15 @@ paint( QPainter* painter, const QStyleOptionGraphicsItem* option, QWidget* widge
     }
 }
 
+template < class ArrTraits >
+QRectF 
+CurveGraphicsItem< ArrTraits >::
+boundingRect( ) const
+{
+    QRectF boundingRectangle = this->convert( this->boundingBox );
+    return boundingRectangle;
+}
+
 template < class ArrTraits >
 void 
 CurveGraphicsItem< ArrTraits >::
@@ -116,15 +136,214 @@ clear( )
     this->curves.clear( );
 }
 
+
+
 template < class ArrTraits >
-QRectF 
+void
 CurveGraphicsItem< ArrTraits >::
-boundingRect( ) const
+setScene( QGraphicsScene* scene_ )
 {
-    QRectF boundingRectangle = this->convert( this->boundingBox );
-    return boundingRectangle;
+    this->scene = scene_;
 }
 
+template < class ArrTraits >
+QRectF
+CurveGraphicsItem< ArrTraits >::
+viewportRect( ) const
+{
+    QRectF res;
+    if ( ! this->scene )
+        return res;
+    if ( this->scene->views( ).size( ) == 0 )
+        return res;
+
+    QGraphicsView* view = this->scene->views( ).first( );
+    QPointF p1 = view->mapToScene( 0, 0 );
+    QPointF p2 = view->mapToScene( view->width( ), view->height( ) );
+    res = QRectF( p1, p2 );
+    return res;
+}
+
+/**
+Specialization of the base template CurveGraphicsItem:
+
+    updateBoundingBox
+*/
+template < class Kernel_ >
+class CurveGraphicsItem< CGAL::Arr_linear_traits_2< Kernel_ > > : public GraphicsItem
+{
+public: // typedefs
+    // known curve types
+    typedef CGAL::Arr_linear_traits_2< Kernel_ > Traits;
+    typedef Kernel_ Kernel;
+    typedef typename Traits::Curve_2 Curve_2;
+    typedef typename Traits::X_monotone_curve_2 X_monotone_curve_2;
+    typedef typename Kernel::Segment_2 Segment_2;
+    typedef typename Kernel::Line_2 Line_2;
+    typedef typename Kernel::Ray_2 Ray_2;
+
+public: // ctors
+    CurveGraphicsItem( ):
+        painterOstream( 0 ),
+        boundingBox( 0, 0, 0, 0 ),
+        boundingBoxInitialized( false ),
+        scene( 0 )
+    {
+        this->setZValue( 4 );
+    }
+
+public: // methods
+    virtual void paint( QPainter* painter, const QStyleOptionGraphicsItem* option, QWidget* widget )
+    {
+        QRectF clippingRectangle = this->viewportRect( );
+        painter->setPen( QPen( ::Qt::red, 0. ) );
+        this->painterOstream = ArrangementPainterOstream< Traits >( painter, clippingRectangle );
+        for ( int i = 0; i < this->curves.size( ); ++i )
+        {
+            X_monotone_curve_2 curve = this->curves[ i ];
+            this->painterOstream << curve;
+        }
+    }
+
+    void insert( const X_monotone_curve_2& curve )
+    {
+        this->curves.push_back( curve );
+    }
+
+    void clear( )
+    {
+        this->curves.clear( );
+    }
+
+    QRectF boundingRect( ) const
+    {
+        QRectF res;
+        if ( ! this->scene )
+        {
+            return res;
+        }
+
+    }
+
+    void setScene( QGraphicsScene* scene_ )
+    {
+        this->scene = scene_;
+        if ( this->scene )
+        {
+            QRectF clipRect = this->viewportRect( );
+            this->convert = CGAL::Qt::Converter< Kernel >( clipRect );
+        }
+    }
+
+public slots:
+    void modelChanged( )
+    {
+        if ( this->curves.size( ) == 0 )
+        {
+            this->hide( );
+        }
+        else
+        {
+            this->show( );
+        }
+        this->updateBoundingBox( );
+        this->update( );
+    }
+
+protected: // methods
+    void updateBoundingBox( )
+    {
+        this->boundingBoxInitialized = 0;
+        this->boundingBox = CGAL::Bbox_2( 0, 0, 0, 0 );
+        QRectF clipRect = this->viewportRect( );
+        if ( !clipRect.isValid( ) )
+        {
+            return;
+        }
+        this->convert = CGAL::Qt::Converter< Kernel >( clipRect );
+
+        bool first = 1;
+        for ( int i = 0; i < curves.size( ); ++i )
+        {
+            X_monotone_curve_2 curve = curves[ i ];
+            if ( curve.is_segment( ) )
+            {
+                Segment_2 seg = curve.segment( );
+                CGAL::Bbox_2 seg_bbox = seg.bbox( );
+                if ( first )
+                {
+                    first = 0;
+                    this->boundingBoxInitialized = 1;
+                    this->boundingBox = seg_bbox;
+                }
+                else
+                {
+                    this->boundingBox = this->boundingBox + seg_bbox;
+                }
+            }
+            else if ( curve.is_ray( ) )
+            {
+                Ray_2 ray = curve.ray( );
+                QLineF qclippedRay = this->convert( ray );
+                if ( qclippedRay.isNull( ) )
+                    continue;
+                Segment_2 clippedRay = this->convert( qclippedRay );
+                if ( first )
+                {
+                    first = 0;
+                    this->boundingBoxInitialized = 1;
+                    this->boundingBox = clippedRay.bbox( );
+                }
+                else
+                {
+                    this->boundingBox = this->boundingBox + clippedRay.bbox( );
+                }
+            }
+            else // curve.is_line( )
+            {
+                Line_2 line = curve.line( );
+                QLineF qclippedLine = this->convert( line );
+                if ( qclippedLine.isNull( ) )
+                    continue;
+                Segment_2 clippedLine = this->convert( qclippedLine );
+                if ( first )
+                {
+                    first = 0;
+                    this->boundingBoxInitialized = 1;
+                    this->boundingBox = clippedLine.bbox( );
+                }
+                else
+                {
+                    this->boundingBox = this->boundingBox + clippedLine.bbox( );
+                }
+            }
+        }
+    }
+
+    QRectF viewportRect( ) const
+    {
+        QRectF res;
+        if ( ! this->scene )
+            return res;
+        if ( this->scene->views( ).size( ) == 0 )
+            return res;
+
+        QGraphicsView* view = this->scene->views( ).first( );
+        QPointF p1 = view->mapToScene( 0, 0 );
+        QPointF p2 = view->mapToScene( view->width( ), view->height( ) );
+        res = QRectF( p1, p2 );
+        return res;
+    }
+
+protected: // fields
+    CGAL::Qt::Converter< Kernel > convert;
+    ArrangementPainterOstream< Traits > painterOstream;
+    std::vector< X_monotone_curve_2 > curves;
+    CGAL::Bbox_2 boundingBox;  
+    bool boundingBoxInitialized;
+    QGraphicsScene* scene;
+}; // class CurveGraphicsItem
+
 } // namespace Qt
 } // namespace CGAL
 
diff --git a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/DeleteCurveCallback.h b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/DeleteCurveCallback.h
index 58523921689..742c57e9d1c 100644
--- a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/DeleteCurveCallback.h
+++ b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/DeleteCurveCallback.h
@@ -70,6 +70,7 @@ DeleteCurveCallback< Arr_ >::
 setScene( QGraphicsScene* scene_ )
 {
     this->scene = scene_;
+    this->highlightedCurve->setScene( scene_ );
     if ( this->scene )
     {
         this->scene->addItem( this->highlightedCurve );
@@ -162,6 +163,7 @@ highlightNearestCurve( QGraphicsSceneMouseEvent* event )
     }
 #endif
     Find_nearest_edge< Arr_ > findNearestEdge( this->arr );
+    findNearestEdge.setScene( this->scene );
     Halfedge_const_handle nearestEdge = findNearestEdge( p );
     this->removableHalfedge = this->arr->non_const_handle( nearestEdge );
 
@@ -170,6 +172,7 @@ highlightNearestCurve( QGraphicsSceneMouseEvent* event )
     //if ( isFirst )
     if ( this->removableHalfedge == Halfedge_handle( ) )
     {
+        std::cout << "no curve found" << std::endl;
         return;
     }
 
diff --git a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/EnvelopeCallback.h b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/EnvelopeCallback.h
index 88e9c86e35d..864b56b3377 100644
--- a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/EnvelopeCallback.h
+++ b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/EnvelopeCallback.h
@@ -33,6 +33,9 @@ public:
     typedef typename Traits::Construct_x_monotone_curve_2 Construct_x_monotone_curve_2;
     typedef typename ArrTraitsAdaptor< Traits >::Kernel Kernel;
     typedef typename Kernel::Point_2 Point_2;
+    typedef typename Kernel::Segment_2 Segment_2;
+    typedef typename Kernel::Ray_2 Ray_2;
+    typedef typename Kernel::Line_2 Line_2;
     typedef CGAL::Envelope_diagram_1< Traits > Diagram_1;
 
     /**
@@ -136,6 +139,8 @@ updateEnvelope( bool lower )
 
     typename Diagram_1::Edge_const_handle e = diagram.leftmost( );
     typename Diagram_1::Vertex_const_handle v;
+    QRectF clipRect = this->viewportRect( );
+    CGAL::Qt::Converter< Kernel > convert( clipRect );
     while ( e != diagram.rightmost( ) )
     {
         if ( ! e->is_empty( ) )
@@ -147,8 +152,27 @@ updateEnvelope( bool lower )
 
             // TODO: generate a subcurve instead of just making a segment
 
-            Point_2 leftPoint = e->left( )->point( );
-            Point_2 rightPoint = e->right( )->point( );
+            Point_2 leftPoint, rightPoint;
+            if ( e->left( ) != NULL )
+            {
+                leftPoint = e->left( )->point( );
+            }
+            else
+            {
+                std::cout << "handle unbounded curve" << std::endl;
+                v = e->right( );
+                e = v->right( );
+                continue;
+            }
+
+            if ( e->right( ) != NULL )
+            {
+                rightPoint = e->right( )->point( );
+            }
+            else
+            {
+                std::cout << "pRight is null; should never get here..." << std::endl;
+            }
             X_monotone_curve_2 curve =
                 this->construct_x_monotone_subcurve_2( e->curve( ), leftPoint, rightPoint );
             envelopeToUpdate->insert( curve );
diff --git a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/GraphicsViewCurveInput.h b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/GraphicsViewCurveInput.h
index 19b73fbd6a2..93532f91483 100644
--- a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/GraphicsViewCurveInput.h
+++ b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/GraphicsViewCurveInput.h
@@ -3,6 +3,7 @@
 #include <CGAL/Arr_segment_traits_2.h>
 #include <CGAL/Arr_polyline_traits_2.h>
 #include <CGAL/Arr_conic_traits_2.h>
+#include <CGAL/Arr_linear_traits_2.h>
 #include <CGAL/Qt/GraphicsViewInput.h>
 #include <CGAL/Qt/Converter.h>
 #include <QEvent>
@@ -21,7 +22,7 @@ class GraphicsViewCurveInputBase:
 {
 public:
     virtual void setScene( QGraphicsScene* scene_ );
-    QGraphicsScene* getScene( ) const;
+    virtual QGraphicsScene* getScene( ) const;
 
     void setSnappingEnabled( bool b );
     void setSnapToGridEnabled( bool b );
@@ -493,6 +494,142 @@ protected:
     ConicType conicType;
 }; // class GraphicsViewCurveInput< CGAL::Arr_conic_traits_2< RatKernel, AlgKernel, NtTraits > >
 
+/**
+Specialization of GraphicsViewCurveInput for Arr_linear_traits_2; handles
+user-guided generation of line segment curves.
+*/
+template < class Kernel_ >
+class GraphicsViewCurveInput< CGAL::Arr_linear_traits_2< Kernel_ > >:
+    public GraphicsViewCurveInputBase
+{
+public: // typedefs
+    typedef Kernel_ Kernel;
+    typedef GraphicsViewCurveInputBase Superclass;
+    typedef CGAL::Arr_linear_traits_2< Kernel > Traits;
+    typedef typename Traits::Curve_2 Curve_2;
+    typedef typename Kernel::Point_2 Point_2;
+    typedef typename Kernel::Segment_2 Segment_2;
+    typedef typename Kernel::Ray_2 Ray_2;
+    typedef typename Kernel::Line_2 Line_2;
+    enum CurveType
+    {
+        SEGMENT, RAY, LINE
+    };
+
+public: // constructors
+    GraphicsViewCurveInput( QObject* parent ):
+        GraphicsViewCurveInputBase( parent ),
+        second( false ),
+        curveType( SEGMENT )
+    { }
+
+public: // methods
+    void setCurveType( CurveType type )
+    {
+        this->curveType = type;
+    }
+
+protected: // methods
+    virtual bool eventFilter( QObject* obj, QEvent* event )
+    {
+        // before we do anything, update the clipping rect
+        // TODO: somehow only update this when the view changes
+        QRectF clippingRect = this->viewportRect( );
+        this->convert = Converter< Kernel >( clippingRect );
+
+        // now handle the event
+        return Superclass::eventFilter( obj, event );
+    }
+
+    void mouseMoveEvent( QGraphicsSceneMouseEvent* event )
+    {
+        if ( this->second )
+        {
+            Point_2 hoverPoint = this->snapPoint( event );
+            if ( p1 == hoverPoint )
+                return;
+            QLineF qSegment;
+            if ( this->curveType == SEGMENT )
+            {
+                Segment_2 segment( this->p1, hoverPoint );
+                qSegment = this->convert( segment );
+            }
+            else if ( this->curveType == RAY )
+            {
+                Ray_2 ray( this->p1, hoverPoint );
+                qSegment = this->convert( ray );
+            }
+            else // this->curveType == LINE
+            {
+                Line_2 line( this->p1, hoverPoint );
+                qSegment = this->convert( line );
+            }
+            this->segmentGuide.setLine( qSegment );
+        }
+    }
+
+    void mousePressEvent( QGraphicsSceneMouseEvent* event )
+    {
+        if ( !this->second )
+        { // fix our first point
+            this->second = true;
+            this->p1 = this->snapPoint( event );
+            QPointF pt = this->convert( this->p1 );
+            this->segmentGuide.setLine( pt.x( ), pt.y( ), pt.x( ), pt.y( ) );
+            if ( this->scene != NULL )
+            {
+                this->scene->addItem( &( this->segmentGuide ) );
+            }
+        }
+        else // this->second == true
+        {
+            this->second = false;
+            this->p2 = this->snapPoint( event );
+
+            // skip if degenerate
+            if ( this->p1 == this->p2 )
+                return;
+
+            if ( this->scene != NULL )
+            {
+                this->scene->removeItem( &( this->segmentGuide ) );
+            }
+
+            Curve_2 res;
+            if ( this->curveType == SEGMENT )
+            {
+                res = Curve_2( Segment_2( this->p1, this->p2 ) );
+            }
+            else if ( this->curveType == RAY )
+            {
+                res = Curve_2( Ray_2( this->p1, this->p2 ) );
+            }
+            else // this->curveType == LINE
+            {
+                res = Curve_2( Line_2( this->p1, this->p2 ) );
+            }
+
+            emit generate( CGAL::make_object( res ) );
+        }
+    }
+
+    // override this to snap to the points you like
+    virtual Point_2 snapPoint( QGraphicsSceneMouseEvent* event )
+    {
+        Point_2 clickedPoint = this->convert( event->scenePos( ) );
+        return clickedPoint;
+    }
+
+protected: // fields
+    Converter< Kernel > convert;
+    Point_2 p1;
+    Point_2 p2;
+    bool second;
+
+    QGraphicsLineItem segmentGuide;
+    CurveType curveType;
+}; // class GraphicsViewCurveInput< CGAL::Arr_linear_traits_2< Kernel_ > >
+
 } // namespace Qt
 } // namespace CGAL
 #endif // CGAL_QT_GRAPHICS_VIEW_SEGMENT_INPUT_H
diff --git a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/MergeEdgeCallback.h b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/MergeEdgeCallback.h
index bd6da8ed9e9..4f52591a9da 100644
--- a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/MergeEdgeCallback.h
+++ b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/MergeEdgeCallback.h
@@ -75,6 +75,8 @@ MergeEdgeCallback< Arr_ >::
 setScene( QGraphicsScene* scene_ )
 {
     this->scene = scene_;
+    this->highlightedCurve->setScene( scene_ );
+    this->highlightedCurve2->setScene( scene_ );
     if ( this->scene )
     {
         this->scene->addItem( this->highlightedCurve );
diff --git a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/NewTabDialog.cpp b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/NewTabDialog.cpp
index a8742f2e48a..9c64251baf0 100644
--- a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/NewTabDialog.cpp
+++ b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/NewTabDialog.cpp
@@ -14,6 +14,7 @@ NewTabDialog( QWidget* parent, Qt::WindowFlags f ):
     this->buttonGroup->addButton( this->ui->segmentRadioButton, ArrangementDemoWindow::SEGMENT_TRAITS );
     this->buttonGroup->addButton( this->ui->polylineRadioButton, ArrangementDemoWindow::POLYLINE_TRAITS );
     this->buttonGroup->addButton( this->ui->conicRadioButton, ArrangementDemoWindow::CONIC_TRAITS );
+    this->buttonGroup->addButton( this->ui->linearRadioButton, ArrangementDemoWindow::LINEAR_TRAITS );
 }
 
 int
diff --git a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/NewTabDialog.ui b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/NewTabDialog.ui
index 837946a923b..2d648fa5d74 100644
--- a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/NewTabDialog.ui
+++ b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/NewTabDialog.ui
@@ -7,7 +7,7 @@
     <x>0</x>
     <y>0</y>
     <width>400</width>
-    <height>133</height>
+    <height>165</height>
    </rect>
   </property>
   <property name="windowTitle">
@@ -19,7 +19,7 @@
      <x>10</x>
      <y>10</y>
      <width>381</width>
-     <height>113</height>
+     <height>141</height>
     </rect>
    </property>
    <layout class="QGridLayout" name="gridLayout">
@@ -50,7 +50,7 @@
       </property>
      </widget>
     </item>
-    <item row="3" column="0">
+    <item row="4" column="0">
      <widget class="QDialogButtonBox" name="buttonBox">
       <property name="orientation">
        <enum>Qt::Horizontal</enum>
@@ -60,6 +60,13 @@
       </property>
      </widget>
     </item>
+    <item row="3" column="0">
+     <widget class="QRadioButton" name="linearRadioButton">
+      <property name="text">
+       <string>Linear</string>
+      </property>
+     </widget>
+    </item>
    </layout>
   </widget>
  </widget>
diff --git a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/SplitEdgeCallback.h b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/SplitEdgeCallback.h
index ba6a7cf912d..c3d32171fac 100644
--- a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/SplitEdgeCallback.h
+++ b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/SplitEdgeCallback.h
@@ -153,8 +153,8 @@ mousePressEvent( QGraphicsSceneMouseEvent* event )
             if ( CGAL::assign( pair, res ) )
             {
                 Point_2 splitPoint = pair.first;
-                if ( this->areEqual( hei->source( )->point( ), splitPoint ) ||
-                    this->areEqual( hei->target( )->point( ), splitPoint ) )
+                if ( ( ! hei->source( )->is_at_open_boundary( ) && this->areEqual( hei->source( )->point( ), splitPoint ) ) ||
+                    ( ! hei->target( )->is_at_open_boundary( ) && this->areEqual( hei->target( )->point( ), splitPoint ) ) )
                 {
                     continue;
                 }
diff --git a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/Utils.h b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/Utils.h
index c91ffead24e..d3bd1ec94d9 100644
--- a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/Utils.h
+++ b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/Utils.h
@@ -26,6 +26,15 @@ public:
     typedef typename ArrTraits::Point_2 Point_2;
 };
 
+template < class Kernel_ >
+class ArrTraitsAdaptor< CGAL::Arr_linear_traits_2< Kernel_ > >
+{
+public:
+    typedef Kernel_ Kernel;
+    typedef CGAL::Arr_linear_traits_2< Kernel > ArrTraits;
+    typedef typename ArrTraits::Point_2 Point_2;
+};
+
 template < class SegmentTraits >
 class ArrTraitsAdaptor< CGAL::Arr_polyline_traits_2< SegmentTraits > >
 {
@@ -51,6 +60,12 @@ public:
     typedef typename ArrTraitsAdaptor< ArrTraits >::Kernel Kernel;
     typedef typename Kernel::FT FT;
 
+public: // ctors
+    Compute_squared_distance_2_base( ):
+        scene( 0 )
+    { }
+
+public: // methods
     template < class T1, class T2 >
     FT
     operator() ( const T1& t1, const T2& t2 ) const
@@ -58,8 +73,36 @@ public:
         return this->squared_distance( t1, t2 );
     }
 
-protected:
+    void setScene( QGraphicsScene* scene_ )
+    {
+        this->scene = scene_;
+    }
+
+    QRectF viewportRect( ) const
+    {
+        QRectF res;
+        if ( this->scene == NULL )
+        {
+            return res;
+        }
+
+        QList< QGraphicsView* > views = this->scene->views( );
+        if ( views.size( ) == 0 )
+        {
+            return res;
+        }
+        // assumes the first view is the right one
+        QGraphicsView* viewport = views.first( );
+        QPointF p1 = viewport->mapToScene( 0, 0 );
+        QPointF p2 = viewport->mapToScene( viewport->width( ), viewport->height( ) );
+        res = QRectF( p1, p2 );
+
+        return res;
+    }
+
+protected: // fields
     typename Kernel::Compute_squared_distance_2 squared_distance;
+    QGraphicsScene* scene;
 };
 
 template < class ArrTraits >
@@ -89,6 +132,44 @@ public:
     }
 };
 
+template < class Kernel_ >
+class Compute_squared_distance_2< CGAL::Arr_linear_traits_2< Kernel_ > > :
+    public Compute_squared_distance_2_base< CGAL::Arr_linear_traits_2< Kernel_ > >
+{
+public:
+    typedef Kernel_ Kernel;
+    typedef CGAL::Arr_linear_traits_2< Kernel > Traits;
+    typedef Compute_squared_distance_2_base< Traits > Superclass;
+    typedef typename Kernel::FT FT;
+    typedef typename Kernel::Point_2 Point_2;
+    typedef typename Kernel::Segment_2 Segment_2;
+    typedef typename Kernel::Ray_2 Ray_2;
+    typedef typename Kernel::Line_2 Line_2;
+    typedef typename Traits::X_monotone_curve_2 X_monotone_curve_2;
+
+    FT operator() ( const Point_2& p, const X_monotone_curve_2& c ) const
+    {
+        Segment_2 seg;
+        Ray_2 ray;
+        Line_2 line;
+        if ( c.is_segment( ) )
+        {
+            seg = c.segment( );
+            return this->squared_distance( p, seg );
+        }
+        else if ( c.is_ray( ) )
+        {
+            ray = c.ray( );
+            return this->squared_distance( p, ray );
+        }
+        else // ( c.is_line( ) )
+        {
+            line = c.line( );
+            return this->squared_distance( p, line );
+        }
+    }
+};
+
 template < class Kernel_ >
 class Compute_squared_distance_2< CGAL::Arr_polyline_traits_2< Kernel_ > > :
     public Compute_squared_distance_2_base< CGAL::Arr_polyline_traits_2< Kernel_ > >
@@ -145,6 +226,7 @@ public:
     typedef typename Traits::Curve_2 Curve_2;
     typedef typename Traits::X_monotone_curve_2 X_monotone_curve_2;
 
+public: // methods
     FT operator() ( const Point_2& p, const X_monotone_curve_2& c ) const
     {
         // Get the co-ordinates of the curve's source and target.
@@ -178,7 +260,20 @@ public:
             FT min_dist( 100000000 );
             AlgKernel ker;
 
-            int n = 100; // TODO: get an adaptive approximation
+            int n = 100;
+            if ( this->scene != NULL && this->scene->views( ).size( ) != 0 )
+            { // use the scene to approximate the resolution of the curve
+                QGraphicsView* view = this->scene->views( ).first( );
+                CGAL::Bbox_2 bb = c.bbox( ); // assumes bounded curve
+                int xmin = view->mapFromScene( bb.xmin( ), bb.ymin( ) ).x( );
+                int xmax = view->mapFromScene( bb.xmax( ), bb.ymin( ) ).x( );
+                n = xmax - xmin;
+                if ( n < 2 )
+                {
+                    n = 2;
+                }
+            }
+
             std::pair< double, double >* app_pts = new std::pair< double, double >[ n + 1 ];
             std::pair< double, double >* end_pts = c.polyline_approximation( n, app_pts );
             std::pair< double, double >* p_curr = app_pts;
@@ -192,7 +287,7 @@ public:
                 FT dist = CGAL::squared_distance( p, seg );
                 if ( first || dist < min_dist )
                 {
-                    first = true;
+                    first = false;
                     min_dist = dist;
                 }
 
@@ -249,6 +344,7 @@ public:
         if ( this->compare_x_2( pLeft, pMin ) == CGAL::LARGER )
         {
             // FIXME: handle vertical lines properly
+            // FIXME: handle unbounded lines properly
             CGAL::Bbox_2 c_bbox = curve.bbox( );
             FT splitLineYMin( c_bbox.ymin( ) - 1.0 );
             FT splitLineYMax( c_bbox.ymax( ) + 1.0 );
@@ -346,6 +442,36 @@ public:
     }
 }; // class Construct_x_monotone_subcurve_2 for Arr_conic_traits_2
 
+template < class Kernel_ >
+class Construct_x_monotone_subcurve_2< CGAL::Arr_linear_traits_2< Kernel_ > >
+{
+public: // typedefs
+    typedef CGAL::Arr_linear_traits_2< Kernel_ > ArrTraits;
+    typedef typename ArrTraits::X_monotone_curve_2 X_monotone_curve_2;
+    typedef Kernel_ Kernel;
+    typedef typename Kernel::Point_2 Point_2;
+    typedef typename Kernel::Segment_2 Segment_2;
+
+public: // methods
+    // curve can be unbounded. if curve is unbounded to the left, pLeft is a point on the left edge of viewport.
+    X_monotone_curve_2 operator() ( const X_monotone_curve_2& curve, const Point_2& pLeft, const Point_2& pRight )
+    {
+        if ( curve.is_segment( ) )
+        {
+            Segment_2 subsegment = this->constructSubsegment( curve.segment( ), pLeft, pRight );
+            return X_monotone_curve_2( subsegment );
+        }
+        else if ( curve.is_ray( ) )
+        {
+
+        }
+        return curve;
+    }
+
+protected:
+    Construct_x_monotone_subcurve_2< CGAL::Arr_segment_traits_2< Kernel_ > > constructSubsegment;
+};
+
 
 template < class K_ >
 class SnapStrategy
@@ -536,12 +662,51 @@ protected:
     CGAL::Qt::Converter< Kernel > convert;
 }; // class SnapToArrangementVertexStrategy
 
-template < class Arr_ >
-class Find_nearest_edge
+class Find_nearest_edge_base
+{
+public:
+    Find_nearest_edge_base( ):
+        scene( 0 )
+    { }
+
+public:
+    virtual void setScene( QGraphicsScene* scene_ )
+    {
+        this->scene = scene_;
+    }
+
+    QRectF viewportRect( ) const
+    {
+        QRectF res;
+        if ( this->scene == NULL )
+        {
+            return res;
+        }
+
+        QList< QGraphicsView* > views = this->scene->views( );
+        if ( views.size( ) == 0 )
+        {
+            return res;
+        }
+        // assumes the first view is the right one
+        QGraphicsView* viewport = views.first( );
+        QPointF p1 = viewport->mapToScene( 0, 0 );
+        QPointF p2 = viewport->mapToScene( viewport->width( ), viewport->height( ) );
+        res = QRectF( p1, p2 );
+
+        return res;
+    }
+
+protected:
+    QGraphicsScene* scene;
+};
+
+template < class Arr_, class ArrTraits = typename Arr_::Geometry_traits_2 >
+class Find_nearest_edge : public Find_nearest_edge_base
 {
 public: // typedefs
     typedef Arr_ Arrangement;
-    typedef typename Arrangement::Geometry_traits_2 ArrTraits;
+    //typedef typename Arrangement::Geometry_traits_2 ArrTraits;
     typedef Compute_squared_distance_2< ArrTraits > Point_curve_distance;
     typedef typename ArrTraits::X_monotone_curve_2 X_monotone_curve_2;
     typedef CGAL::Arr_walk_along_line_point_location< Arrangement > Point_location_strategy;
@@ -557,6 +722,7 @@ public: // typedefs
 
 public: // constructors
     Find_nearest_edge( Arrangement* arr_ ):
+        Find_nearest_edge_base( ),
         arr( arr_ ),
         pointLocationStrategy( Point_location_strategy( *arr_ ) )
     { }
@@ -587,6 +753,159 @@ public: // member methods
             }
             while ( ++cc != face->outer_ccb( ) );
         }
+#if 0 // we can't do this with bounded arrangements
+        else
+        {
+            Ccb_halfedge_const_circulator cc = face->outer_ccb( );
+            do
+            {
+                if ( cc->is_fictitious( ) )
+                {
+                    continue;
+                }
+
+                X_monotone_curve_2 curve = cc->curve( );
+                FT dist = this->pointCurveDistance( queryPt, curve );
+                if ( first || dist < minDist )
+                {
+                    first = 0;
+                    minDist = dist;
+                    closestEdge = cc;
+                }
+            }
+            while ( ++cc != face->outer_ccb( ) );
+        }
+#endif
+        Hole_const_iterator hit; 
+        Hole_const_iterator eit = face->holes_end( );
+        int counter = 0;
+        for ( hit = face->holes_begin( ); hit != eit; ++hit )
+        { // check any holes inside this face
+            Ccb_halfedge_const_circulator cc = *hit;
+            do
+            {
+                X_monotone_curve_2 curve = cc->curve( );
+                FT dist = this->pointCurveDistance( queryPt, curve );
+                if ( first || dist < minDist )
+                {
+                    first = 0;
+                    minDist = dist;
+                    closestEdge = cc;
+                }
+                cc++;
+            }
+            while ( cc != *hit );
+        }
+
+        return closestEdge;
+    }
+
+    virtual void setScene( QGraphicsScene* scene_ )
+    {
+        this->pointCurveDistance.setScene( scene_ );
+        Find_nearest_edge_base::setScene( scene_ );
+    }
+
+protected: // member methods
+    Face_const_handle getFace( const CGAL::Object& obj )
+    {
+        Face_const_handle f;
+        if ( CGAL::assign( f, obj ) )
+            return f;
+
+        Halfedge_const_handle he;
+        if (CGAL::assign( he, obj ))
+            return (he->face( ));
+
+        Vertex_const_handle v;
+        CGAL_assertion(CGAL::assign( v, obj ));
+        CGAL::assign( v, obj );
+        if ( v->is_isolated( ) )
+            return v->face( );
+        Halfedge_around_vertex_const_circulator eit = v->incident_halfedges( );
+        return  (eit->face( ));
+    }
+
+protected: // member fields
+    Arrangement* arr;
+    Point_curve_distance pointCurveDistance;
+    Point_location_strategy pointLocationStrategy;
+
+}; // class Find_nearest_edge
+
+template < class Arr_, class Kernel_ >
+class Find_nearest_edge< Arr_, CGAL::Arr_linear_traits_2< Kernel_ > >: public Find_nearest_edge_base
+{
+public: // typedefs
+    typedef Arr_ Arrangement;
+    typedef typename Arrangement::Geometry_traits_2 ArrTraits;
+    typedef Compute_squared_distance_2< ArrTraits > Point_curve_distance;
+    typedef typename ArrTraits::X_monotone_curve_2 X_monotone_curve_2;
+    typedef CGAL::Arr_walk_along_line_point_location< Arrangement > Point_location_strategy;
+    typedef typename ArrTraitsAdaptor< ArrTraits >::Kernel Kernel;
+    typedef typename Kernel::Point_2 Point_2;
+    typedef typename Arrangement::Face_const_handle Face_const_handle;
+    typedef typename Arrangement::Halfedge_const_handle Halfedge_const_handle;
+    typedef typename Arrangement::Vertex_const_handle Vertex_const_handle;
+    typedef typename Arrangement::Ccb_halfedge_const_circulator Ccb_halfedge_const_circulator;
+    typedef typename Point_curve_distance::FT FT;
+    typedef typename Arrangement::Hole_const_iterator Hole_const_iterator;
+    typedef typename Arrangement::Halfedge_around_vertex_const_circulator Halfedge_around_vertex_const_circulator;
+
+public: // constructors
+    Find_nearest_edge( Arrangement* arr_ ):
+        Find_nearest_edge_base( ),
+        arr( arr_ ),
+        pointLocationStrategy( Point_location_strategy( *arr_ ) )
+    { }
+
+public: // member methods
+    Halfedge_const_handle operator()( const Point_2& queryPt )
+    {
+        CGAL::Object pointLocationResult = this->pointLocationStrategy.locate( queryPt );
+        Face_const_handle face = this->getFace( pointLocationResult );
+        bool first = 1;
+        X_monotone_curve_2 closestCurve;
+        Halfedge_const_handle closestEdge;
+        FT minDist( 0 );
+
+        if ( ! face->is_unbounded( ) )
+        { // it is an interior face so it has a ccb
+            Ccb_halfedge_const_circulator cc = face->outer_ccb( );
+            do
+            {
+                X_monotone_curve_2 curve = cc->curve( );
+                FT dist = this->pointCurveDistance( queryPt, curve );
+                if ( first || dist < minDist )
+                {
+                    first = 0;
+                    minDist = dist;
+                    closestEdge = cc;
+                }
+            }
+            while ( ++cc != face->outer_ccb( ) );
+        }
+        else
+        {
+            Ccb_halfedge_const_circulator cc = face->outer_ccb( );
+            do
+            {
+                if ( cc->is_fictitious( ) )
+                {
+                    continue;
+                }
+
+                X_monotone_curve_2 curve = cc->curve( );
+                FT dist = this->pointCurveDistance( queryPt, curve );
+                if ( first || dist < minDist )
+                {
+                    first = 0;
+                    minDist = dist;
+                    closestEdge = cc;
+                }
+            }
+            while ( ++cc != face->outer_ccb( ) );
+        }
         Hole_const_iterator hit; 
         Hole_const_iterator eit = face->holes_end( );
         for ( hit = face->holes_begin( ); hit != eit; ++hit )
@@ -634,7 +953,7 @@ protected: // member fields
     Arrangement* arr;
     Point_curve_distance pointCurveDistance;
     Point_location_strategy pointLocationStrategy;
-
 }; // class Find_nearest_edge
 
+
 #endif // CGAL_ARRANGEMENTS_DEMO_UTILS_H
diff --git a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/VerticalRayShootCallback.h b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/VerticalRayShootCallback.h
index 9f1f784ad9f..d773db19e79 100644
--- a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/VerticalRayShootCallback.h
+++ b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/VerticalRayShootCallback.h
@@ -115,6 +115,7 @@ VerticalRayShootCallback< Arr_ >::
 setScene( QGraphicsScene* scene_ )
 {
     this->scene = scene_;
+    this->highlightedCurves->setScene( scene_ );
     if ( this->scene )
     {
         this->scene->addItem( this->highlightedCurves );