diff --git a/.gitattributes b/.gitattributes
index 5a6183a5bfe..f3188cd2506 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -3105,6 +3105,7 @@ Polyhedron/demo/Polyhedron/MainWindow.ui -text
 Polyhedron/demo/Polyhedron/Polyhedron_3.qrc -text
 Polyhedron/demo/Polyhedron/data/anchor.off -text svneol=unset#application/octet-stream
 Polyhedron/demo/Polyhedron/data/cow.off -text svneol=unset#application/octet-stream
+Polyhedron/demo/Polyhedron/data/cross.off -text svneol=unset#application/octet-stream
 Polyhedron/demo/Polyhedron/data/cube_tri.off -text svneol=unset#application/octet-stream
 Polyhedron/demo/Polyhedron/data/ellipsoid.off -text svneol=unset#application/octet-stream
 Polyhedron/demo/Polyhedron/data/knot.off -text svneol=unset#application/octet-stream
diff --git a/Polyhedron/demo/Polyhedron/MainWindow.h b/Polyhedron/demo/Polyhedron/MainWindow.h
index aafe0eaf325..95cb281f824 100644
--- a/Polyhedron/demo/Polyhedron/MainWindow.h
+++ b/Polyhedron/demo/Polyhedron/MainWindow.h
@@ -50,6 +50,7 @@ protected slots:
   void on_actionActivatePolyhedron_triggered();
   void on_actionSetPolyhedronA_triggered();
   void on_actionSetPolyhedronB_triggered();
+	void on_actionInsideOut_triggered();
 
   // save
   // TODO: save all, save current (do we store the current file name?)
diff --git a/Polyhedron/demo/Polyhedron/MainWindow.ui b/Polyhedron/demo/Polyhedron/MainWindow.ui
index 843cf452591..dbf2627f1d5 100644
--- a/Polyhedron/demo/Polyhedron/MainWindow.ui
+++ b/Polyhedron/demo/Polyhedron/MainWindow.ui
@@ -188,7 +188,7 @@
     <addaction name="menuSubdivision" />
     <addaction name="actionSimplify" />
     <addaction name="menu_Boolean_operations" />
-    <addaction name="actionInside_out" />
+    <addaction name="actionInsideOut" />
    </widget>
    <widget class="QMenu" name="menuView" >
     <property name="title" >
@@ -536,7 +536,7 @@
     <string>Ctrl+B</string>
    </property>
   </action>
-  <action name="actionInside_out" >
+  <action name="actionInsideOut" >
    <property name="text" >
     <string>Inside-out</string>
    </property>
diff --git a/Polyhedron/demo/Polyhedron/MainWindow_inside_out.cpp b/Polyhedron/demo/Polyhedron/MainWindow_inside_out.cpp
new file mode 100644
index 00000000000..874859a3841
--- /dev/null
+++ b/Polyhedron/demo/Polyhedron/MainWindow_inside_out.cpp
@@ -0,0 +1,19 @@
+#include "MainWindow.h"
+#include "Scene.h"
+
+void MainWindow::on_actionInsideOut_triggered()
+{
+  if(onePolygonIsSelected())
+  {
+    // get selected polyhedron
+    int index = getSelectedPolygonIndex();
+    Polyhedron* pMesh = scene->polyhedron(index);
+
+		// inside out
+		pMesh->inside_out();
+
+    // update scene
+    scene->polyhedronChanged(index);
+    QApplication::restoreOverrideCursor();
+  }
+}
diff --git a/Polyhedron/demo/Polyhedron/MainWindow_kernel.cpp b/Polyhedron/demo/Polyhedron/MainWindow_kernel.cpp
index d6612eb193c..ab0f851732d 100644
--- a/Polyhedron/demo/Polyhedron/MainWindow_kernel.cpp
+++ b/Polyhedron/demo/Polyhedron/MainWindow_kernel.cpp
@@ -28,7 +28,7 @@ void MainWindow::on_actionKernel_triggered()
     // solve LP 
     std::cout << "Solve linear program...";
     Polyhedron_kernel kernel;
-    if(kernel.solve(triangles.begin(),triangles.end()))
+    if(!kernel.solve(triangles.begin(),triangles.end()))
     {
       std::cout << "empty kernel" << std::endl;
       return;
diff --git a/Polyhedron/demo/Polyhedron/data/cross.off b/Polyhedron/demo/Polyhedron/data/cross.off
new file mode 100644
index 00000000000..9623f6f97ed
--- /dev/null
+++ b/Polyhedron/demo/Polyhedron/data/cross.off
@@ -0,0 +1,118 @@
+OFF
+40 76 114
+-4.44089e-016 3 0
+1 3 0
+2 3 0
+2 4 0
+2 5 0
+3 5 0
+3 4 0
+3 3 0
+4 3 0
+5 3 0
+5 2 0
+4 2 0
+3 2 0
+3 1 0
+3 -4.44089e-016 0
+2 -4.44089e-016 0
+2 1 0
+2 2 0
+1 2 0
+-4.44089e-016 2 0
+-4.44089e-016 3 1
+1 3 1
+2 3 1
+2 4 1
+2 5 1
+3 5 1
+3 4 1
+3 3 1
+4 3 1
+5 3 1
+5 2 1
+4 2 1
+3 2 1
+3 1 1
+3 -4.44089e-016 1
+2 -4.44089e-016 1
+2 1 1
+2 2 1
+1 2 1
+-4.44089e-016 2 1
+3   19 0 1 
+3   18 1 2 
+3   17 2 7 
+3   7 2 3 
+3   6 3 4 
+3   12 7 8 
+3   11 8 9 
+3   17 12 13 
+3   16 13 14 
+3   21 1 0 
+3   22 2 1 
+3   23 3 2 
+3   24 4 3 
+3   25 5 4 
+3   26 6 5 
+3   27 7 6 
+3   28 8 7 
+3   29 9 8 
+3   30 10 9 
+3   31 11 10 
+3   32 12 11 
+3   33 13 12 
+3   34 14 13 
+3   35 15 14 
+3   36 16 15 
+3   37 17 16 
+3   38 18 17 
+3   39 19 18 
+3   20 0 19 
+3   20 39 38 
+3   21 38 37 
+3   22 37 32 
+3   22 27 26 
+3   23 26 25 
+3   27 32 31 
+3   28 31 30 
+3   32 37 36 
+3   33 36 35 
+3   1 18 19 
+3   2 17 18 
+3   7 12 17 
+3   3 6 7 
+3   4 5 6 
+3   8 11 12 
+3   9 10 11 
+3   13 16 17 
+3   14 15 16 
+3   0 20 21 
+3   1 21 22 
+3   2 22 23 
+3   3 23 24 
+3   4 24 25 
+3   5 25 26 
+3   6 26 27 
+3   7 27 28 
+3   8 28 29 
+3   9 29 30 
+3   10 30 31 
+3   11 31 32 
+3   12 32 33 
+3   13 33 34 
+3   14 34 35 
+3   15 35 36 
+3   16 36 37 
+3   17 37 38 
+3   18 38 39 
+3   19 39 20 
+3   38 21 20 
+3   37 22 21 
+3   32 27 22 
+3   26 23 22 
+3   25 24 23 
+3   31 28 27 
+3   30 29 28 
+3   36 33 32 
+3   35 34 33 
diff --git a/Polyhedron/demo/Polyhedron/include/CGAL/Polyhedron_kernel.h b/Polyhedron/demo/Polyhedron/include/CGAL/Polyhedron_kernel.h
index 4715591b84a..1d62d95b0c5 100644
--- a/Polyhedron/demo/Polyhedron/include/CGAL/Polyhedron_kernel.h
+++ b/Polyhedron/demo/Polyhedron/include/CGAL/Polyhedron_kernel.h
@@ -2,7 +2,6 @@
 #include <CGAL/QP_functions.h>
 #include <CGAL/QP_models.h>
 
-
 // Taken from http://www.qhull.org/html/qhalf.htm
 
 // If you do not know an interior point for the halfspaces, use linear programming
@@ -74,7 +73,7 @@ public:
 
 		int j = 0;
 		InputIterator it;
-		for(it = begin; it != end; it++)
+		for(it = begin; it != end; it++, j++)
 		{
 			const Triangle& triangle = *it;
 			const Point& a = triangle[0];
@@ -94,7 +93,7 @@ public:
 			lp.set_a(index_x4, j, -1.0); // -x4
 
 			// right hand side (>= -dj)
-			FT dj = distance_to_origin(plane);
+			FT dj = distance_to_origin(plane) * CGAL::sign(plane.d());
 			lp.set_b(j, -dj);  
 		}
 
diff --git a/Polyhedron/demo/Polyhedron/main.cpp b/Polyhedron/demo/Polyhedron/main.cpp
index 233092b5260..91ed400e3ea 100644
--- a/Polyhedron/demo/Polyhedron/main.cpp
+++ b/Polyhedron/demo/Polyhedron/main.cpp
@@ -36,6 +36,7 @@ int main(int argc, char **argv)
 #include "MainWindow_subdivision_methods.cpp"
 #include "MainWindow_self_intersection.cpp"
 #include "MainWindow_convex_hull.cpp"
+#include "MainWindow_inside_out.cpp"
 #include "MainWindow_simplify.cpp"
 #include "MainWindow_kernel.cpp"
 #include "MainWindow_pca.cpp"