diff --git a/Straight_skeleton_2/include/CGAL/Straight_skeleton_2.h b/Straight_skeleton_2/include/CGAL/Straight_skeleton_2.h
index 3cf2b00fcb0..046f41fa362 100644
--- a/Straight_skeleton_2/include/CGAL/Straight_skeleton_2.h
+++ b/Straight_skeleton_2/include/CGAL/Straight_skeleton_2.h
@@ -213,7 +213,7 @@ public :
           if ( begin->is_border())
               ++nb;
       }
-      CGAL_STSKEL_VALIDITY_TRACE("summe border halfedges (2*nb) = " << 2 * nb );
+      CGAL_STSKEL_VALIDITY_TRACE("sum of border halfedges (2*nb) = " << 2 * nb );
 
       bool nvalid = ( n == this->size_of_halfedges());
 
diff --git a/Straight_skeleton_2/include/CGAL/Straight_skeleton_2/Polygon_offset_builder_2_impl.h b/Straight_skeleton_2/include/CGAL/Straight_skeleton_2/Polygon_offset_builder_2_impl.h
index 95fe522f3b3..7d94e9a603d 100644
--- a/Straight_skeleton_2/include/CGAL/Straight_skeleton_2/Polygon_offset_builder_2_impl.h
+++ b/Straight_skeleton_2/include/CGAL/Straight_skeleton_2/Polygon_offset_builder_2_impl.h
@@ -66,7 +66,8 @@ Polygon_offset_builder_2<Ss,Gt,Cont,Visitor>::LocateHook( FT
     Halfedge_const_handle lNext = aBisector->next();
 
     CGAL_POLYOFFSET_TRACE(2,"Testing hook on " << e2str(*aBisector) ) ;
-    CGAL_POLYOFFSET_TRACE(4, "Next: " << e2str(*lNext) << " ; Prev: " << e2str(*lPrev) ) ;
+    CGAL_POLYOFFSET_TRACE(4, "Next: " << e2str(*lNext) ) ;
+    CGAL_POLYOFFSET_TRACE(4, "Prev: " << e2str(*lPrev) ) ;
 
     if ( !IsVisited(aBisector) )
     {
diff --git a/Straight_skeleton_2/include/CGAL/Straight_skeleton_2/Straight_skeleton_builder_2_impl.h b/Straight_skeleton_2/include/CGAL/Straight_skeleton_2/Straight_skeleton_builder_2_impl.h
index f163c0fdd4b..9819ba88568 100644
--- a/Straight_skeleton_2/include/CGAL/Straight_skeleton_2/Straight_skeleton_builder_2_impl.h
+++ b/Straight_skeleton_2/include/CGAL/Straight_skeleton_2/Straight_skeleton_builder_2_impl.h
@@ -46,6 +46,8 @@ Straight_skeleton_builder_2<Gt,Ss,V>::Straight_skeleton_builder_2 ( boost::optio
  ,mPQ(mEventCompare)
  ,mSSkel( new SSkel() )
 {
+  if( mMaxTime )
+    CGAL_STSKEL_BUILDER_TRACE(4, "Init with mMaxTime = " << *mMaxTime)
 }
 
 template<class Gt, class Ss, class V>
@@ -98,6 +100,9 @@ Straight_skeleton_builder_2<Gt,Ss,V>::FindEdgeEvent( Vertex_handle aLNode, Verte
   {
     Trisegment_2_ptr lTrisegment = CreateTrisegment(lTriedge,aLNode,aRNode);
 
+    CGAL_STSKEL_BUILDER_TRACE(4, "\n[] Considering E" << lTrisegment->e0().mID << " E" << lTrisegment->e1().mID << " E" << lTrisegment->e2().mID
+                                << " Collinearity: " << trisegment_collinearity_to_string(lTrisegment->collinearity()) ) ;
+
     // The 02 collinearity configuration is problematic: 01 or 12 collinearity has a seed position
     // giving the point through which the bisector passes. However, for 02, it is not a given.
     //
@@ -163,7 +168,9 @@ Straight_skeleton_builder_2<Gt,Ss,V>::FindEdgeEvent( Vertex_handle aLNode, Verte
       }
       else
       {
-        CGAL_STSKEL_BUILDER_TRACE(4, "Edge event: " << lTriedge << " is in the past. Compared to L=" << lLNodeD << " to R=" << lRNodeD ) ;
+        CGAL_STSKEL_BUILDER_TRACE(4, "Edge event: " << lTriedge << " is in the past." ) ;
+        CGAL_STSKEL_BUILDER_TRACE(4, "\tCompared to L=" << aLNode->id() << " (" << lLNodeD << ")" ) ;
+        CGAL_STSKEL_BUILDER_TRACE(4, "\tCompared to R=" << aRNode->id() << " (" << lRNodeD << ")" ) ;
       }
     }
   }
@@ -605,6 +612,8 @@ void Straight_skeleton_builder_2<Gt,Ss,V>::CreateContourBisectors()
 template<class Gt, class Ss, class V>
 void Straight_skeleton_builder_2<Gt,Ss,V>::HarmonizeSpeeds(boost::mpl::bool_<true>)
 {
+  CGAL_STSKEL_BUILDER_TRACE ( 2, "Harmonize speeds..." ) ;
+
   // Collinear input edges might not have the exact same speed if an inexact square root is used.
   // This might cause some inconsistencies in time, resulting in invalid skeletons. Therefore,
   // if the square root is not exact, we enforce that collinear input edges have the same speed,
@@ -1058,7 +1067,7 @@ void Straight_skeleton_builder_2<Gt,Ss,V>::HandleEdgeEvent( EventPtr aEvent )
     SetBisectorSlope(lLSeed,lNewNode);
     SetBisectorSlope(lRSeed,lNewNode);
 
-    CGAL_STSKEL_BUILDER_TRACE( 1, "E" << e2str(*(lRSeed->halfedge()->defining_contour_edge())) << " collapsed." );
+    CGAL_STSKEL_BUILDER_TRACE( 1, e2str(*(lRSeed->halfedge()->defining_contour_edge())) << " collapsed." );
     CGAL_STSKEL_BUILDER_TRACE( 3, "fictitious node along collapsed face is N" << lRIFicNode->id()
                                << " between " << e2str(*lROBisector) << " and " << e2str(*lLIBisector) ) ;
 
@@ -1539,16 +1548,16 @@ void Straight_skeleton_builder_2<Gt,Ss,V>::Propagate()
     if ( !mPQ.empty() )
     {
 #ifdef CGAL_SLS_PRINT_QUEUE_BEFORE_EACH_POP
-      std::cout << "MAIN QUEUE -------------------------------------------------- " << std::endl;
-      std::cout << "Queue size: " << mPQ.size() << std::endl;
+      CGAL_STSKEL_BUILDER_TRACE(4, "MAIN QUEUE -------------------------------------------------- ");
+      CGAL_STSKEL_BUILDER_TRACE(4, "Queue size: " << mPQ.size());
       auto mpq = mPQ;
       while(!mpq.empty())
       {
         EventPtr event = mpq.top();
         mpq.pop();
-        std::cout << *event << std::endl;
+        CGAL_STSKEL_BUILDER_TRACE(4, *event);
       }
-      std::cout << "END MAIN QUEUE --------------------------------------------- " << std::endl;
+      CGAL_STSKEL_BUILDER_TRACE(4, "END MAIN QUEUE --------------------------------------------- ");
 #endif
 
       EventPtr lEvent = PopEventFromPQ();
@@ -2031,7 +2040,7 @@ bool Straight_skeleton_builder_2<Gt,Ss,V>::FinishUp()
 
   mVisitor.on_cleanup_finished();
 
-  // @todo if 'mMaxTime' is sufficiently large, it will be a full skeleton and should be validated as such
+  // If 'mMaxTime' is sufficiently large, it will be a full skeleton and could be validated as such...
   if(mMaxTime) // might be a partial skeleton
     return mSSkel->is_valid(true);
   else
diff --git a/Straight_skeleton_2/include/CGAL/Straight_skeleton_2/Straight_skeleton_builder_events_2.h b/Straight_skeleton_2/include/CGAL/Straight_skeleton_2/Straight_skeleton_builder_events_2.h
index fba2f93c1d6..10dce56f03b 100644
--- a/Straight_skeleton_2/include/CGAL/Straight_skeleton_2/Straight_skeleton_builder_events_2.h
+++ b/Straight_skeleton_2/include/CGAL/Straight_skeleton_2/Straight_skeleton_builder_events_2.h
@@ -178,7 +178,7 @@ private :
   virtual void dump ( std::ostream& ss ) const
   {
     this->Base::dump(ss);
-    ss << " (Split Event, Seed=" << mSeed->id() << " (" << mSeed->point() << ") OppBorder=" << this->triedge().e2()->id() << ')' ;
+    ss << " (Split Event, Seed=" << mSeed->id() << "pos: (" << mSeed->point() << ") OppBorder=" << this->triedge().e2()->id() << ')' ;
   }
 
 private :
diff --git a/Straight_skeleton_2/include/CGAL/Straight_skeleton_2/debug.h b/Straight_skeleton_2/include/CGAL/Straight_skeleton_2/debug.h
index 72887141335..62ad19c8c4e 100644
--- a/Straight_skeleton_2/include/CGAL/Straight_skeleton_2/debug.h
+++ b/Straight_skeleton_2/include/CGAL/Straight_skeleton_2/debug.h
@@ -22,7 +22,7 @@
 #if    defined(CGAL_STRAIGHT_SKELETON_ENABLE_TRACE) \
     || defined(CGAL_POLYGON_OFFSET_ENABLE_TRACE) \
     || defined(CGAL_STRAIGHT_SKELETON_TRAITS_ENABLE_TRACE) \
-    || defined(CGAL_STRAIGHT_SKELETON_ENABLE_VALIDITY_TRACE) \
+    || defined(CGAL_STRAIGHT_SKELETON_VALIDITY_ENABLE_TRACE) \
     || defined(CGAL_STRAIGHT_SKELETON_ENABLE_INTRINSIC_TESTING)
 #
 #  define CGAL_STSKEL_TRACE_ON
@@ -231,6 +231,7 @@ template<class VH, class Triedge>
 inline std::string newn2str( char const* name, VH const& v, Triedge const& aTriedge )
 {
   std::ostringstream ss ;
+  ss.precision(17);
 
   ss << "New Node " << name <<" is N" << v->id() << " at " << v->point()
      << " [E" << aTriedge.e0()->id()
@@ -283,7 +284,7 @@ bool sEnableTraitsTrace = true;
 #endif
 
 
-#ifdef CGAL_STRAIGHT_SKELETON_ENABLE_VALIDITY_TRACE
+#ifdef CGAL_STRAIGHT_SKELETON_VALIDITY_ENABLE_TRACE
 #  define CGAL_STSKEL_VALIDITY_TRACE(m) CGAL_STSKEL_TRACE(m)
 #  define CGAL_STSKEL_VALIDITY_TRACE_IF(cond,m) if ( cond ) CGAL_STSKEL_VALIDITY_TRACE(m)
 #else
diff --git a/Straight_skeleton_2/include/CGAL/Straight_skeleton_builder_2.h b/Straight_skeleton_2/include/CGAL/Straight_skeleton_builder_2.h
index 33df80101dc..026ab6390fc 100644
--- a/Straight_skeleton_2/include/CGAL/Straight_skeleton_builder_2.h
+++ b/Straight_skeleton_2/include/CGAL/Straight_skeleton_builder_2.h
@@ -447,7 +447,7 @@ private :
     }
   }
 
-  // @todo Should split events always have lower priority than split events?
+  // @todo Should split events always have lower priority than edge events?
   Comparison_result CompareEventsSupportAngles ( EventPtr const& aA, EventPtr const& aB )
   {
     CGAL_precondition ( aA->type() != Event::cEdgeEvent && aB->type() != Event::cEdgeEvent ) ;
@@ -1404,8 +1404,6 @@ public:
       }
     }
 
-    CGAL_assertion_code(std::cout << "lFaceCountThroughWeights = " << lFaceCountThroughWeights << std::endl;)
-    CGAL_assertion_code(std::cout << "mSSkel->SSkel::Base::size_of_faces() = " << mSSkel->SSkel::Base::size_of_faces() << std::endl;)
     CGAL_assertion( lFaceCountThroughWeights == mSSkel->SSkel::Base::size_of_faces() ) ;
 
     return *this;
diff --git a/Straight_skeleton_2/include/CGAL/Straight_skeleton_halfedge_base_2.h b/Straight_skeleton_2/include/CGAL/Straight_skeleton_halfedge_base_2.h
index 2943861ae1a..81e484da4ff 100644
--- a/Straight_skeleton_2/include/CGAL/Straight_skeleton_halfedge_base_2.h
+++ b/Straight_skeleton_2/include/CGAL/Straight_skeleton_halfedge_base_2.h
@@ -89,7 +89,7 @@ public:
   Halfedge_const_handle defining_contour_edge() const { return this->face()->halfedge() ; }
   Halfedge_handle       defining_contour_edge()       { return this->face()->halfedge() ; }
 
-  // @fixme this isn't documented in the `StraightSkeletonHalfedge_2` concept
+  // @fixme below is not documented in the `StraightSkeletonHalfedge_2` concept
   Sign slope() const { return mSlope ; }
   void set_slope( Sign aSlope ) { mSlope = aSlope ; }
 
diff --git a/Straight_skeleton_2/include/CGAL/Trisegment_2.h b/Straight_skeleton_2/include/CGAL/Trisegment_2.h
index 3f85a626b10..f16b8de4919 100644
--- a/Straight_skeleton_2/include/CGAL/Trisegment_2.h
+++ b/Straight_skeleton_2/include/CGAL/Trisegment_2.h
@@ -156,10 +156,10 @@ public:
 
   friend std::ostream& operator << ( std::ostream& os, Self const& aTrisegment )
   {
-    return os << "[" << s2str(aTrisegment.e0())
-              << " " << s2str(aTrisegment.e1())
-              << " " << s2str(aTrisegment.e2())
-              << " " << trisegment_collinearity_to_string(aTrisegment.collinearity())
+    return os << "[e0 " << s2str(aTrisegment.e0())
+              << "; e1 " << s2str(aTrisegment.e1())
+              << "; e2 " << s2str(aTrisegment.e2())
+              << "; Collinearity: " << trisegment_collinearity_to_string(aTrisegment.collinearity())
               << "]";
   }
 
diff --git a/Straight_skeleton_2/include/CGAL/constructions/Polygon_offset_cons_ftC2.h b/Straight_skeleton_2/include/CGAL/constructions/Polygon_offset_cons_ftC2.h
index 03b25b3352d..87873753b21 100644
--- a/Straight_skeleton_2/include/CGAL/constructions/Polygon_offset_cons_ftC2.h
+++ b/Straight_skeleton_2/include/CGAL/constructions/Polygon_offset_cons_ftC2.h
@@ -48,7 +48,9 @@ boost::optional< Point_2<K> > construct_offset_pointC2 ( typename K::FT const& t
 
   FT x(0.0),y(0.0) ;
 
-  CGAL_STSKEL_TRAITS_TRACE("Constructing offset point for t=" << t << " e0=" << s2str(e0) << " e1=" << s2str(e1) << " tri=" << tri ) ;
+  CGAL_STSKEL_TRAITS_TRACE("Constructing offset point for t=" << t ) ;
+  CGAL_STSKEL_TRAITS_TRACE("Edges " << " e0=" << s2str(e0) << " w = " << weight0 ) ;
+  CGAL_STSKEL_TRAITS_TRACE(            " e1=" << s2str(e1) << " w = " << weight1 << " tri=" << tri ) ;
 
   Optional_line_2 l0 = compute_normalized_line_ceoffC2(e0, aCoeff_cache) ;
   Optional_line_2 l1 = compute_normalized_line_ceoffC2(e1, aCoeff_cache) ;
diff --git a/Straight_skeleton_2/include/CGAL/constructions/Straight_skeleton_cons_ftC2.h b/Straight_skeleton_2/include/CGAL/constructions/Straight_skeleton_cons_ftC2.h
index 8ffd6f68eee..8df825fdb6a 100644
--- a/Straight_skeleton_2/include/CGAL/constructions/Straight_skeleton_cons_ftC2.h
+++ b/Straight_skeleton_2/include/CGAL/constructions/Straight_skeleton_cons_ftC2.h
@@ -142,8 +142,7 @@ boost::optional< Line_2<K> > compute_normalized_line_ceoffC2( Segment_2<K> const
       c = e.source().y();
     }
 
-    CGAL_STSKEL_TRAITS_TRACE("Unweighted line coefficients for HORIZONTAL line:\n"
-                            << s2str(e)
+    CGAL_STSKEL_TRAITS_TRACE("Unweighted line coefficients for HORIZONTAL line: " << s2str(e)
                             << "\na="<< n2str(a) << ", b=" << n2str(b) << ", c=" << n2str(c)
                            ) ;
   }
@@ -166,8 +165,7 @@ boost::optional< Line_2<K> > compute_normalized_line_ceoffC2( Segment_2<K> const
       c = -e.source().x();
     }
 
-    CGAL_STSKEL_TRAITS_TRACE("Unweighted line coefficients for VERTICAL line:\n"
-                            << s2str(e)
+    CGAL_STSKEL_TRAITS_TRACE("Unweighted line coefficients for VERTICAL line: " << s2str(e)
                             << "\na="<< n2str(a) << ", b=" << n2str(b) << ", c=" << n2str(c)
                            ) ;
   }
@@ -186,8 +184,7 @@ boost::optional< Line_2<K> > compute_normalized_line_ceoffC2( Segment_2<K> const
 
       c = -e.source().x()*a - e.source().y()*b;
 
-      CGAL_STSKEL_TRAITS_TRACE("Unweighted line coefficients for line:\n"
-                               << s2str(e)
+      CGAL_STSKEL_TRAITS_TRACE("Unweighted line coefficients for line: " << s2str(e)
                                << "\nsa="<< n2str(sa) << "\nsb=" << n2str(sb) << "\nl2=" << n2str(l2) << "\nl=" << n2str(l)
                                << "\na="<< n2str(a) << "\nb=" << n2str(b) << "\nc=" << n2str(c)
                                ) ;
@@ -211,9 +208,8 @@ boost::optional< Line_2<K> > compute_normalized_line_ceoffC2( Segment_2<K> const
   CGAL_precondition( CGAL_NTS is_finite(b) ) ;
   CGAL_precondition( CGAL_NTS is_finite(c) ) ;
 
-  CGAL_STSKEL_TRAITS_TRACE("Weighted line coefficients for line:\n"
-                            << s2str(e)
-                            << "\nscaling=" << n2str(lScale)
+  CGAL_STSKEL_TRAITS_TRACE("Weighted line coefficients for line: " << s2str(e)
+                            << "\nweight=" << n2str(aWeight)
                             << "\na="<< n2str(a) << "\nb=" << n2str(b) << "\nc=" << n2str(c)
                             ) ;
 
@@ -312,8 +308,8 @@ compute_normal_offset_lines_isec_timeC2 ( boost::intrusive_ptr< Trisegment_2<K,
   // or 'time', can be computed solving for 't' in the linear system formed by 3 such equations.
   // The result is :
   //
-  //  t = a2*b0*c1 - a2*b1*c0 - b2*a0*c1 + b2*a1*c0 + b1*a0*c2 - b0*a1*c2
-  //      ---------------------------------------------------------------
+  //      a2*b0*c1 - a2*b1*c0 - b2*a0*c1 + b2*a1*c0 + b1*a0*c2 - b0*a1*c2
+  //  t = ---------------------------------------------------------------
   //             -a2*b1 + a2*b0 + b2*a1 - b2*a0 + b1*a0 - b0*a1 ;
 
   bool ok = false ;
@@ -368,8 +364,9 @@ boost::optional< Point_2<K> > compute_oriented_midpoint ( Segment_2_with_ID<K> c
   if ( CGAL_NTS is_finite(delta01) &&  CGAL_NTS is_finite(delta10) )
   {
     if ( delta01 <= delta10 )
-         mp = CGAL::midpoint(e0.target(),e1.source());
-    else mp = CGAL::midpoint(e1.target(),e0.source());
+      mp = CGAL::midpoint(e0.target(),e1.source());
+    else
+      mp = CGAL::midpoint(e1.target(),e0.source());
 
     CGAL_STSKEL_TRAITS_TRACE("Computing oriented midpoint between:"
                              << "\ne0: " << s2str(e0)
@@ -668,7 +665,7 @@ construct_normal_offset_lines_isecC2 ( boost::intrusive_ptr< Trisegment_2<K, Seg
   {
     FT den = l0->a()*l2->b() - l0->a()*l1->b() - l1->a()*l2->b() + l2->a()*l1->b() + l0->b()*l1->a() - l0->b()*l2->a();
 
-    CGAL_STSKEL_TRAITS_TRACE("den=" << n2str(den) )
+    CGAL_STSKEL_TRAITS_TRACE("\tden=" << n2str(den) )
 
     if ( ! CGAL_NTS certified_is_zero(den) )
     {
@@ -682,9 +679,8 @@ construct_normal_offset_lines_isecC2 ( boost::intrusive_ptr< Trisegment_2<K, Seg
         x =  numX / den ;
         y = -numY / den ;
 
-       CGAL_STSKEL_TRAITS_TRACE("numX=" << n2str(numX) << "\nnumY=" << n2str(numY)
-                               << "\nx=" << n2str(x) << "\ny=" << n2str(y)
-                               )
+       CGAL_STSKEL_TRAITS_TRACE("\tnumX=" << n2str(numX) << "\n\tnumY=" << n2str(numY)
+                                << "\n\tx=" << n2str(x) << "\n\ty=" << n2str(y) ) ;
       }
     }
   }
@@ -704,6 +700,7 @@ construct_normal_offset_lines_isecC2 ( boost::intrusive_ptr< Trisegment_2<K, Seg
 //
 // POSTCONDITION: In case of overflow an empty optional is returned.
 //
+// See detailed computations in compute_degenerate_offset_lines_isec_timeC2()
 template <class K, class CoeffCache>
 boost::optional< Point_2<K> >
 construct_degenerate_offset_lines_isecC2 ( boost::intrusive_ptr< Trisegment_2<K, Segment_2_with_ID<K> > > const& tri,
@@ -717,7 +714,9 @@ construct_degenerate_offset_lines_isecC2 ( boost::intrusive_ptr< Trisegment_2<K,
   typedef boost::optional<Point_2> Optional_point_2 ;
   typedef boost::optional<Line_2>  Optional_line_2 ;
 
-  CGAL_STSKEL_TRAITS_TRACE("Computing degenerate offset lines isec point for: " << tri )  ;
+  CGAL_STSKEL_TRAITS_TRACE("Computing degenerate offset lines isec point for:"
+                           << " E" << tri->e0().mID << ",E" << tri->e1().mID << ",E" << tri->e2().mID << std::endl
+                           << tri ) ;
 
   FT x(0.0),y(0.0) ;
 
@@ -824,7 +823,7 @@ construct_degenerate_offset_lines_isecC2 ( boost::intrusive_ptr< Trisegment_2<K,
     }
   }
 
-  CGAL_STSKEL_TRAITS_TRACE("\nDegenerate " << (CGAL_NTS is_zero(l0->b()) ? "(vertical)" : "") << " event point:  x=" << n2str(x) << " y=" << n2str(y) )
+  CGAL_STSKEL_TRAITS_TRACE("\nDegenerate" << (CGAL_NTS is_zero(l0->b()) ? " (vertical)" : "") << " event point:  x=" << n2str(x) << " y=" << n2str(y) )
 
   return cgal_make_optional(ok,K().construct_point_2_object()(x,y)) ;
 }
diff --git a/Straight_skeleton_2/include/CGAL/create_offset_polygons_2.h b/Straight_skeleton_2/include/CGAL/create_offset_polygons_2.h
index dbaa31bbcb8..39ee6bec9cc 100644
--- a/Straight_skeleton_2/include/CGAL/create_offset_polygons_2.h
+++ b/Straight_skeleton_2/include/CGAL/create_offset_polygons_2.h
@@ -389,7 +389,7 @@ create_exterior_skeleton_and_offset_polygons_2(const FT& aOffset,
            ofk);
 }
 
-// Overloads common to both polygons with and without holes, a simple polygons are returned in any case
+// Overloads common to both polygons with and without holes, a simple polygons is returned in any case
 template<class FT, class APolygon, class OfK,
          class OutPolygon = typename CGAL_SS_i::Default_return_polygon_type<APolygon, OfK>::type>
 std::vector< boost::shared_ptr<OutPolygon> >
diff --git a/Straight_skeleton_2/include/CGAL/create_weighted_straight_skeleton_2.h b/Straight_skeleton_2/include/CGAL/create_weighted_straight_skeleton_2.h
index 6c72defa00d..d0837c9c7c4 100644
--- a/Straight_skeleton_2/include/CGAL/create_weighted_straight_skeleton_2.h
+++ b/Straight_skeleton_2/include/CGAL/create_weighted_straight_skeleton_2.h
@@ -195,6 +195,8 @@ create_exterior_weighted_straight_skeleton_2(const FT& max_offset,
     frame[2] = Point_2(fxmax,fymax);
     frame[3] = Point_2(fxmin,fymax);
 
+    CGAL_STSKEL_BUILDER_TRACE(2, "Frame:\n" << frame[0] << "\n" << frame[1] << "\n" << frame[2] << "\n" << frame[3]);
+
     typedef std::vector<Point_2> Hole;
 
     Hole poly(vertices_begin, vertices_end);
diff --git a/Straight_skeleton_2/include/CGAL/predicates/Straight_skeleton_pred_ftC2.h b/Straight_skeleton_2/include/CGAL/predicates/Straight_skeleton_pred_ftC2.h
index 0a70ea188c9..6f3dedf9d92 100644
--- a/Straight_skeleton_2/include/CGAL/predicates/Straight_skeleton_pred_ftC2.h
+++ b/Straight_skeleton_2/include/CGAL/predicates/Straight_skeleton_pred_ftC2.h
@@ -187,6 +187,8 @@ Uncertain<bool> exist_offset_lines_isec2 ( boost::intrusive_ptr< Trisegment_2<K,
 
   Uncertain<bool> rResult = Uncertain<bool>::indeterminate();
 
+  CGAL_STSKEL_TRAITS_TRACE( "Checking existence of an event for E" << tri->e0().mID << " E" << tri->e1().mID << " E" << tri->e2().mID ) ;
+
   if ( tri->collinearity() != TRISEGMENT_COLLINEARITY_ALL )
   {
     CGAL_STSKEL_TRAITS_TRACE( ( tri->collinearity() == TRISEGMENT_COLLINEARITY_NONE ? " normal edges" : " collinear edges" ) ) ;
@@ -206,25 +208,27 @@ Uncertain<bool> exist_offset_lines_isec2 ( boost::intrusive_ptr< Trisegment_2<K,
           if ( aMaxTime && CGAL_NTS certainly(rResult) )
             rResult = CGAL_NTS certified_is_smaller_or_equal(tq,Quotient(*aMaxTime));
 
-          CGAL_STSKEL_TRAITS_TRACE("\nEvent time: " << *t << ". Event " << ( rResult ? "exist." : "doesn't exist." ) ) ;
+          CGAL_STSKEL_TRAITS_TRACE("Event time: " << *t << ". Event " << ( rResult ? "exist." : "doesn't exist." ) ) ;
         }
         else
         {
-          CGAL_STSKEL_TRAITS_TRACE("\nDenominator exactly zero, Event doesn't exist." ) ;
+          CGAL_STSKEL_TRAITS_TRACE("Denominator exactly zero, Event doesn't exist." ) ;
           rResult = false;
         }
       }
-      else{
-        CGAL_STSKEL_TRAITS_TRACE("\nDenominator is probably zero (but not exactly), event existence is indeterminate." ) ;
+      else
+      {
+        CGAL_STSKEL_TRAITS_TRACE("Denominator is probably zero (but not exactly), event existence is indeterminate." ) ;
       }
     }
-    else{
-      CGAL_STSKEL_TRAITS_TRACE("\nEvent time overflowed, event existence is indeterminate." ) ;
+    else
+    {
+      CGAL_STSKEL_TRAITS_TRACE("Event time overflowed, event existence is indeterminate." ) ;
     }
   }
   else
   {
-    CGAL_STSKEL_TRAITS_TRACE("\nAll the edges are collinear. Event doesn't exist." ) ;
+    CGAL_STSKEL_TRAITS_TRACE("All the edges are collinear. Event doesn't exist." ) ;
     rResult = false;
   }