diff --git a/common/geometry/shape_line_chain.cpp b/common/geometry/shape_line_chain.cpp
index d5b974bb1e..d0437b41e5 100644
--- a/common/geometry/shape_line_chain.cpp
+++ b/common/geometry/shape_line_chain.cpp
@@ -29,16 +29,15 @@ using boost::optional;
 
 bool SHAPE_LINE_CHAIN::Collide( const VECTOR2I& aP, int aClearance ) const
 {
-    assert( false );
-
-    return false;
+	// fixme: ugly!
+    SEG s(aP, aP);
+    return this->Collide(s, aClearance);
 }
 
 
 bool SHAPE_LINE_CHAIN::Collide( const BOX2I& aBox, int aClearance ) const
 {
     assert( false );
-
     return false;
 }
 
diff --git a/include/geometry/seg.h b/include/geometry/seg.h
index af8161bb80..9c87ff478e 100644
--- a/include/geometry/seg.h
+++ b/include/geometry/seg.h
@@ -215,14 +215,34 @@ public:
      */
     bool Collinear( const SEG& aSeg ) const
     {
-        ecoord qa1 = A.y - B.y;
-        ecoord qb1 = B.x - A.x;
-        ecoord qc1 = -qa1 * A.x - qb1 * A.y;
-        ecoord qa2 = aSeg.A.y - aSeg.B.y;
-        ecoord qb2 = aSeg.B.x - aSeg.A.x;
-        ecoord qc2 = -qa2 * aSeg.A.x - qb2 * aSeg.A.y;
+        ecoord qa = A.y - B.y;
+        ecoord qb = B.x - A.x;
+        ecoord qc = -qa * A.x - qb * A.y;
 
-        return ( qa1 == qa2 ) && ( qb1 == qb2 ) && ( qc1 == qc2 );
+        ecoord d1 = std::abs( aSeg.A.x * qa + aSeg.A.y * qb + qc );
+        ecoord d2 = std::abs( aSeg.B.x * qa + aSeg.B.y * qb + qc );
+
+        return ( d1 <= 1 && d2 <= 1 );
+    }
+
+    bool Overlaps ( const SEG& aSeg ) const
+    {
+        if( aSeg.A == aSeg.B ) // single point corner case
+        {
+            if(A == aSeg.A || B == aSeg.A)
+                return false;
+
+            return Contains(aSeg.A);
+        }
+
+        if( !Collinear (aSeg ))
+            return false;
+
+        if ( Contains (aSeg.A) || Contains(aSeg.B) )
+            return true;
+        if ( aSeg.Contains (A) || aSeg.Contains(B) )
+            return true;
+        return false;
     }
 
     /**
diff --git a/include/geometry/shape.h b/include/geometry/shape.h
index 7ba77b671b..25f242b054 100644
--- a/include/geometry/shape.h
+++ b/include/geometry/shape.h
@@ -40,7 +40,10 @@ enum SHAPE_TYPE
     SH_RECT = 0,        ///> axis-aligned rectangle
     SH_SEGMENT,         ///> line segment
     SH_LINE_CHAIN,      ///> line chain (polyline)
-    SH_CIRCLE           ///> circle
+    SH_CIRCLE,          ///> circle
+    SH_CONVEX,			///> convex polygon
+    SH_POLYGON,         ///> any polygon (with holes, etc.)
+    SH_COMPOUND         ///> compound shape, consisting of multiple simple shapes
 };
 
 /**
@@ -146,7 +149,11 @@ public:
         return BBox( 0 ).Centre(); // if nothing better is available....
     }
 
-private:
+    virtual void Move ( const VECTOR2I& aVector ) = 0;
+
+    virtual bool IsSolid() const = 0;
+    
+protected:
     ///> type of our shape
     SHAPE_TYPE m_type;
 };
diff --git a/include/geometry/shape_circle.h b/include/geometry/shape_circle.h
index e4b668b68c..2408c72ba8 100644
--- a/include/geometry/shape_circle.h
+++ b/include/geometry/shape_circle.h
@@ -86,6 +86,15 @@ public:
         return m_center;
     }
 
+    void Move ( const VECTOR2I& aVector )
+    {
+        m_center += aVector;
+    }
+
+    bool IsSolid() const
+    {
+        return true;
+    }
 private:
     int m_radius;
     VECTOR2I m_center;
diff --git a/include/geometry/shape_line_chain.h b/include/geometry/shape_line_chain.h
index 8c9c549d98..13ff6cd7c6 100644
--- a/include/geometry/shape_line_chain.h
+++ b/include/geometry/shape_line_chain.h
@@ -103,6 +103,17 @@ public:
         m_points[2] = aC;
     }
 
+    SHAPE_LINE_CHAIN( const VECTOR2I& aA, const VECTOR2I& aB, const VECTOR2I& aC, const VECTOR2I& aD ) :
+        SHAPE( SH_LINE_CHAIN ), m_closed( false )
+    {
+        m_points.resize( 4 );
+        m_points[0] = aA;
+        m_points[1] = aB;
+        m_points[2] = aC;
+        m_points[3] = aD;
+    }
+
+
     SHAPE_LINE_CHAIN(const VECTOR2I* aV, int aCount ) :
         SHAPE( SH_LINE_CHAIN ),
         m_closed( false )
@@ -553,6 +564,16 @@ public:
 
     bool CompareGeometry( const SHAPE_LINE_CHAIN & aOther ) const;
 
+    void Move ( const VECTOR2I& aVector )
+    {
+        for(std::vector<VECTOR2I>::iterator i = m_points.begin(); i != m_points.end(); ++i)
+            (*i) += aVector;
+    }
+
+    bool IsSolid() const
+    {
+        return false;
+    }
 private:
     /// array of vertices
     std::vector<VECTOR2I> m_points;
diff --git a/include/geometry/shape_rect.h b/include/geometry/shape_rect.h
index bc3ba44d17..7b16df89e8 100644
--- a/include/geometry/shape_rect.h
+++ b/include/geometry/shape_rect.h
@@ -159,6 +159,16 @@ public:
         return m_h;
     }
 
+    void Move ( const VECTOR2I& aVector )
+    {
+        m_p0 += aVector;
+    }
+
+    bool IsSolid() const
+    {
+        return true;
+    }
+    
 private:
     ///> Top-left corner
     VECTOR2I m_p0;
diff --git a/include/geometry/shape_segment.h b/include/geometry/shape_segment.h
index 5f18760bd7..203c8485a2 100644
--- a/include/geometry/shape_segment.h
+++ b/include/geometry/shape_segment.h
@@ -82,6 +82,17 @@ public:
 		return m_width;
 	}
 
+	bool IsSolid() const
+	{
+		return true;
+	}
+
+	void Move ( const VECTOR2I& aVector	)
+	{
+		m_seg.A += aVector;
+		m_seg.B += aVector;
+	}
+
 private:
 	SEG m_seg;
 	int m_width;