diff --git a/dumux/freeflow/stokes/stokesfluxvariables.hh b/dumux/freeflow/stokes/stokesfluxvariables.hh
index c338272db454256bb17487520bd3cfe2ef846584..15029d7e9b699306224e7d51087af126f886b35c 100644
--- a/dumux/freeflow/stokes/stokesfluxvariables.hh
+++ b/dumux/freeflow/stokes/stokesfluxvariables.hh
@@ -63,6 +63,7 @@ class StokesFluxVariables
     typedef typename FVElementGeometry::SubControlVolumeFace SCVFace;
 
 public:
+    //! \brief The constructor
     StokesFluxVariables(const Problem &problem,
                         const Element &element,
                         const FVElementGeometry &fvGeometry,
diff --git a/dumux/freeflow/stokes/stokespropertydefaults.hh b/dumux/freeflow/stokes/stokespropertydefaults.hh
index d2fb953ff3470129b0ce5d55b43248b4e805758e..bbd7e996bacf9748f2c48b1c981131544981fa5e 100644
--- a/dumux/freeflow/stokes/stokespropertydefaults.hh
+++ b/dumux/freeflow/stokes/stokespropertydefaults.hh
@@ -78,6 +78,8 @@ SET_TYPE_PROP(BoxStokes, NewtonController, StokesNewtonController<TypeTag>);
 
 #if HAVE_SUPERLU
 SET_TYPE_PROP(BoxStokes, LinearSolver, SuperLUBackend<TypeTag>);
+#elif HAVE_UMFPACK
+SET_TYPE_PROP(BoxStokes, LinearSolver, UMFPackBackend<TypeTag>);
 #endif
 
 //! the Model property
diff --git a/test/freeflow/navierstokes/navierstokestestproblem.hh b/test/freeflow/navierstokes/navierstokestestproblem.hh
index 0c45b1f7025741f5283f8f351250cf3b4873e333..3c06d2e33b3f56bd51ce04df3e124b02afa123a6 100644
--- a/test/freeflow/navierstokes/navierstokestestproblem.hh
+++ b/test/freeflow/navierstokes/navierstokestestproblem.hh
@@ -68,13 +68,11 @@ namespace Dumux
     // Set calculation to Navier-Stokes, not Stokes
     SET_BOOL_PROP(NavierStokesTestProblem, EnableNavierStokes, true);
 
-    SET_PROP(NavierStokesTestProblem, Fluid)
-    {
-    private:
-      typedef typename GET_PROP_TYPE(TypeTag, Scalar) Scalar;
-    public:
-      typedef Dumux::GasPhase<Scalar, Dumux::N2ConstViscosity<Scalar> > type;
-    };
+    // Use nitrogen with a constant viscosity as gas phase
+    SET_TYPE_PROP(NavierStokesTestProblem, Fluid,
+                  Dumux::GasPhase<typename GET_PROP_TYPE(TypeTag, Scalar),
+                                  Dumux::N2ConstViscosity<typename GET_PROP_TYPE(TypeTag, Scalar)> >);
+
     // Scalar is set to type double
     SET_TYPE_PROP(BoxStokes, Scalar, double);
   }
diff --git a/test/freeflow/navierstokes/test_navierstokes.cc b/test/freeflow/navierstokes/test_navierstokes.cc
index 9f035d50e15dfb85618a395e8cad2751be1e8c55..7bb7e20163c56c79ca75a3794a705ee70edb94ce 100644
--- a/test/freeflow/navierstokes/test_navierstokes.cc
+++ b/test/freeflow/navierstokes/test_navierstokes.cc
@@ -55,7 +55,8 @@ int main(int argc, char** argv)
     typedef TTAG(NavierStokesTestProblem) ProblemTypeTag;
     return Dumux::start<ProblemTypeTag>(argc, argv, usage);
 #else
-    std::cout << "Test skipped, it needs SuperLU and ALUGrid or UG." << std::endl;
+#warning "You need to have SuperLU and ALUGrid or UG to run this test."
+    std::cout << "You need to have SuperLU and ALUGrid or UG to run this test." << std::endl;
     return 77;
 #endif
 }
diff --git a/test/freeflow/stokes/stokestestproblem.hh b/test/freeflow/stokes/stokestestproblem.hh
index f6541a442cc2781966cd033d167ad674dfc2ffba..d87fc4558e2bb04c3c4c94ea1f9ae7574ac134ca 100644
--- a/test/freeflow/stokes/stokestestproblem.hh
+++ b/test/freeflow/stokes/stokestestproblem.hh
@@ -49,18 +49,10 @@ SET_TYPE_PROP(StokesTestProblem, Grid, Dune::YaspGrid<2>);
 // Set the problem property
 SET_TYPE_PROP(StokesTestProblem, Problem, Dumux::StokesTestProblem<TypeTag>);
 
-SET_PROP(StokesTestProblem, Fluid)
-{
-private:
-    typedef typename GET_PROP_TYPE(TypeTag, Scalar) Scalar;
-public:
-    typedef Dumux::GasPhase<Scalar, Dumux::N2<Scalar> > type;
-};
-//! Scalar is set to type long double for higher accuracy
-SET_TYPE_PROP(BoxStokes, Scalar, double);
-
-//! Disable unsymmetrized velocity gradient by default
-SET_BOOL_PROP(StokesTestProblem, EnableUnsymmetrizedVelocityGradient, false);
+// Use nitrogen as gas phase
+SET_TYPE_PROP(StokesTestProblem, Fluid,
+              Dumux::GasPhase<typename GET_PROP_TYPE(TypeTag, Scalar),
+                              Dumux::N2<typename GET_PROP_TYPE(TypeTag, Scalar)> >);
 }
 
 /*!
diff --git a/test/freeflow/stokes/test_stokes.cc b/test/freeflow/stokes/test_stokes.cc
index 7515d12576b2390c8e4e9bb35411845e932610cc..bada422a19b4509b11531e2f776c22bf0308f3b8 100644
--- a/test/freeflow/stokes/test_stokes.cc
+++ b/test/freeflow/stokes/test_stokes.cc
@@ -39,8 +39,8 @@ void usage(const char *progName, const std::string &errorMsg)
                     errorMessageOut += " [options]\n";
                     errorMessageOut += errorMsg;
                     errorMessageOut += "\n\nThe List of Mandatory arguments for this program is:\n"
-                                        "\t-TimeManager.TEnd                          The end of the simulation. [s] \n"
-                                        "\t-TimeManager.DtInitial                     The initial timestep size. [s] \n"
+                                        "\t-TimeManager.TEnd               The end of the simulation. [s] \n"
+                                        "\t-TimeManager.DtInitial          The initial timestep size. [s] \n"
                                         "\t-Grid.File                      The file name of the file containing the grid \n"
                                         "\t                                   definition in DGF format\n";
 
@@ -51,12 +51,12 @@ void usage(const char *progName, const std::string &errorMsg)
 
 int main(int argc, char** argv)
 {
-#if HAVE_SUPERLU
+#if (HAVE_SUPERLU || HAVE_UMFPACK)
     typedef TTAG(StokesTestProblem) ProblemTypeTag;
     return Dumux::start<ProblemTypeTag>(argc, argv, usage);
 #else
-#warning "No SuperLU installed. Stokes currently only works with SuperLU."
-    std::cout << "No SuperLU installed. Stokes currently only works with SuperLU." << std::endl;
-    return 1;
+#warning "You need to have SuperLU or UMFPack installed to run this test."
+    std::cerr << "You need to have SuperLU or UMFPack installed to run this test\n";
+    return 77;
 #endif
 }
diff --git a/test/freeflow/stokes2c/stokes2ctestproblem.hh b/test/freeflow/stokes2c/stokes2ctestproblem.hh
index f741805ad0c6148c3413d836564b6e26356c0b38..a3ae5f3433f6f6e8b44c26ca66576b36364cac54 100644
--- a/test/freeflow/stokes2c/stokes2ctestproblem.hh
+++ b/test/freeflow/stokes2c/stokes2ctestproblem.hh
@@ -48,15 +48,9 @@ SET_TYPE_PROP(Stokes2cTestProblem, Grid, Dune::YaspGrid<2>);
 // Set the problem property
 SET_TYPE_PROP(Stokes2cTestProblem, Problem, Dumux::Stokes2cTestProblem<TypeTag>);
 
-//! Select the fluid system
-SET_PROP(BoxStokesnc, FluidSystem)
-{
-    typedef typename GET_PROP_TYPE(TypeTag, Scalar) Scalar;
-    typedef Dumux::FluidSystems::H2OAir<Scalar> type;
-};
-
-//! Scalar is set to type long double for higher accuracy
-//SET_TYPE_PROP(BoxStokes, Scalar, long double);
+// Select the fluid system
+SET_TYPE_PROP(Stokes2cTestProblem, FluidSystem,
+              Dumux::FluidSystems::H2OAir<typename GET_PROP_TYPE(TypeTag, Scalar)>);
 }
 
 /*!
diff --git a/test/freeflow/stokes2c/test_stokes2c.cc b/test/freeflow/stokes2c/test_stokes2c.cc
index 1f198fbd50809cc53d2a29a5a4825924c74db051..3fe68acfb02e8940a9fbaa0e2ab53a8bc39c27a0 100644
--- a/test/freeflow/stokes2c/test_stokes2c.cc
+++ b/test/freeflow/stokes2c/test_stokes2c.cc
@@ -39,8 +39,8 @@ void usage(const char *progName, const std::string &errorMsg)
                     errorMessageOut += " [options]\n";
                     errorMessageOut += errorMsg;
                     errorMessageOut += "\n\nThe List of Mandatory arguments for this program is:\n"
-                                        "\t-TimeManager.TEnd                          The end of the simulation. [s] \n"
-                                        "\t-TimeManager.DtInitial                     The initial timestep size. [s] \n"
+                                        "\t-TimeManager.TEnd               The end of the simulation. [s] \n"
+                                        "\t-TimeManager.DtInitial          The initial timestep size. [s] \n"
                                         "\t-Grid.File                      The file name of the file containing the grid \n"
                                         "\t                                   definition in DGF format\n";
 
@@ -51,12 +51,12 @@ void usage(const char *progName, const std::string &errorMsg)
 
 int main(int argc, char** argv)
 {
-#if HAVE_SUPERLU
+#if (HAVE_SUPERLU || HAVE_UMFPACK)
     typedef TTAG(Stokes2cTestProblem) ProblemTypeTag;
     return Dumux::start<ProblemTypeTag>(argc, argv, usage);
 #else
-#warning "No SuperLU installed. Stokes currently only works with SuperLU."
-    std::cout << "No SuperLU installed. Stokes currently only works with SuperLU." << std::endl;
-    return 1;
+#warning "You need to have SuperLU or UMFPack installed to run this test."
+    std::cerr << "You need to have SuperLU or UMFPack installed to run this test\n";
+    return 77;
 #endif
 }
diff --git a/test/freeflow/stokes2cni/stokes2cnitestproblem.hh b/test/freeflow/stokes2cni/stokes2cnitestproblem.hh
index f8f2750d35a23be985faf82b8d11ee87b1f3b85b..33b187e6c8f7be5c5af3590a5ed859349e655f2c 100644
--- a/test/freeflow/stokes2cni/stokes2cnitestproblem.hh
+++ b/test/freeflow/stokes2cni/stokes2cnitestproblem.hh
@@ -52,22 +52,15 @@ SET_TYPE_PROP(Stokes2cniTestProblem, Grid, Dune::YaspGrid<2>);
 // Set the problem property
 SET_TYPE_PROP(Stokes2cniTestProblem, Problem, Stokes2cniTestProblem<TypeTag>);
 
-//! Select the fluid system
-SET_PROP(Stokes2cniTestProblem, FluidSystem)
-{
-    typedef typename GET_PROP_TYPE(TypeTag, Scalar) Scalar;
-    typedef Dumux::FluidSystems::H2OAir<Scalar> type;
-};
-
-#if HAVE_UMFPACK
-SET_TYPE_PROP(Stokes2cniTestProblem, LinearSolver, UMFPackBackend<TypeTag>);
-#endif
-
-//! Scalar is set to type long double for higher accuracy
-//SET_TYPE_PROP(Stokes2cniTestProblem, Scalar, long double);
+// Select the fluid system
+SET_TYPE_PROP(Stokes2cniTestProblem, FluidSystem,
+              Dumux::FluidSystems::H2OAir<typename GET_PROP_TYPE(TypeTag, Scalar)>);
 
+// Use Pardiso as linear solver, if available
 #if HAVE_PARDISO
 SET_TYPE_PROP(Stokes2cniTestProblem, LinearSolver, PardisoBackend<TypeTag>);
+#elif HAVE_UMFPACK
+SET_TYPE_PROP(Stokes2cniTestProblem, LinearSolver, UMFPackBackend<TypeTag>);
 #endif
 }
 
diff --git a/test/freeflow/stokes2cni/test_stokes2cni.cc b/test/freeflow/stokes2cni/test_stokes2cni.cc
index e86b807108f6b889e911293c779e5679617f9420..ec12d6bce313e26593a8e6aad5802fe4075adade 100644
--- a/test/freeflow/stokes2cni/test_stokes2cni.cc
+++ b/test/freeflow/stokes2cni/test_stokes2cni.cc
@@ -39,8 +39,8 @@ void usage(const char *progName, const std::string &errorMsg)
                     errorMessageOut += " [options]\n";
                     errorMessageOut += errorMsg;
                     errorMessageOut += "\n\nThe List of Mandatory arguments for this program is:\n"
-                                        "\t-TimeManager.TEnd                          The end of the simulation. [s] \n"
-                                        "\t-TimeManager.DtInitial                     The initial timestep size. [s] \n"
+                                        "\t-TimeManager.TEnd               The end of the simulation. [s] \n"
+                                        "\t-TimeManager.DtInitial          The initial timestep size. [s] \n"
                                         "\t-Grid.File                      The file name of the file containing the grid \n"
                                         "\t                                   definition in DGF format\n";
 
@@ -51,12 +51,12 @@ void usage(const char *progName, const std::string &errorMsg)
 
 int main(int argc, char** argv)
 {
-#if HAVE_SUPERLU
+#if (HAVE_PARDISO || HAVE_UMFPACK)
     typedef TTAG(Stokes2cniTestProblem) ProblemTypeTag;
     return Dumux::start<ProblemTypeTag>(argc, argv, usage);
 #else
-#warning "No SuperLU installed. Stokes currently only works with SuperLU."
-    std::cout << "No SuperLU installed. Stokes currently only works with SuperLU." << std::endl;
-    return 1;
+#warning "You need to have Pardiso or UMFPack installed to run this test."
+    std::cerr << "You need to have Pardiso or UMFPack installed to run this test\n";
+    return 77;
 #endif
 }
diff --git a/test/freeflow/zeroeq/test_zeroeq.cc b/test/freeflow/zeroeq/test_zeroeq.cc
index 180c80bcdd9b5750a2af591fb0143d294c4896ed..15f18bae550377599237cb132c37c6695a36ca73 100644
--- a/test/freeflow/zeroeq/test_zeroeq.cc
+++ b/test/freeflow/zeroeq/test_zeroeq.cc
@@ -56,6 +56,12 @@ void usage(const char *progName, const std::string &errorMsg)
 
 int main(int argc, char** argv)
 {
+#if (HAVE_SUPERLU || HAVE_UMFPACK)
     typedef TTAG(ZeroEqTestProblem) ProblemTypeTag;
     return Dumux::start<ProblemTypeTag>(argc, argv, usage);
+#else
+#warning "You need to have SuperLU or UMFPack installed to run this test."
+    std::cerr << "You need to have SuperLU or UMFPack installed to run this test\n";
+    return 77;
+#endif
 }
diff --git a/test/freeflow/zeroeq/test_zeroeq_channel.cc b/test/freeflow/zeroeq/test_zeroeq_channel.cc
index 41ab633685d0b5b822a3b5dce061d6e030ad6bfc..09bff71eddd9acbb501b9fd1d6081a2983c40528 100644
--- a/test/freeflow/zeroeq/test_zeroeq_channel.cc
+++ b/test/freeflow/zeroeq/test_zeroeq_channel.cc
@@ -57,6 +57,12 @@ void usage(const char *progName, const std::string &errorMsg)
 
 int main(int argc, char** argv)
 {
+#if HAVE_UMFPACK
     typedef TTAG(ZeroEqChannelTestProblem) ProblemTypeTag;
     return Dumux::start<ProblemTypeTag>(argc, argv, usage);
+#else
+#warning "You need to have UMFPack installed to run this test."
+    std::cerr << "You need to have UMFPack installed to run this test\n";
+    return 77;
+#endif
 }
diff --git a/test/freeflow/zeroeq/zeroeqchanneltestproblem.hh b/test/freeflow/zeroeq/zeroeqchanneltestproblem.hh
index 30de8649836c939ea77a1250dc5a2741a5785983..84278a81251ff5220a564202f4adc326c8c1018a 100644
--- a/test/freeflow/zeroeq/zeroeqchanneltestproblem.hh
+++ b/test/freeflow/zeroeq/zeroeqchanneltestproblem.hh
@@ -55,14 +55,10 @@ SET_TYPE_PROP(ZeroEqChannelTestProblem, Grid, Dune::YaspGrid<2>);
 // Set the problem property
 SET_TYPE_PROP(ZeroEqChannelTestProblem, Problem, Dumux::ZeroEqChannelTestProblem<TypeTag>);
 
-// Set the fluids
-SET_PROP(ZeroEqChannelTestProblem, Fluid)
-{
-private:
-    typedef typename GET_PROP_TYPE(TypeTag, Scalar) Scalar;
-public:
-    typedef Dumux::GasPhase<Scalar, Dumux::Air<Scalar> > type;
-};
+// Set the air as the gas phase
+SET_TYPE_PROP(ZeroEqChannelTestProblem, Fluid,
+              Dumux::GasPhase<typename GET_PROP_TYPE(TypeTag, Scalar),
+                              Dumux::Air<typename GET_PROP_TYPE(TypeTag, Scalar)> >);
 
 // Disable gravity
 SET_BOOL_PROP(ZeroEqChannelTestProblem, ProblemEnableGravity, false);
@@ -72,6 +68,11 @@ SET_BOOL_PROP(ZeroEqChannelTestProblem, BBoxMaxIsWall, false);
 
 // Do not write sub-control volume data
 SET_SCALAR_PROP(ZeroEqChannelTestProblem, ZeroEqWriteAllSCVData, -1);
+
+#if HAVE_UMFPACK
+// Use UMFPack as linear solver
+SET_TYPE_PROP(ZeroEqChannelTestProblem, LinearSolver, UMFPackBackend<TypeTag>);
+#endif
 }
 
 /*!
diff --git a/test/freeflow/zeroeq/zeroeqtestproblem.hh b/test/freeflow/zeroeq/zeroeqtestproblem.hh
index a85845fac78830b190efaff9da214b5a826ad62a..e13159c30c3d769637202151a7a99dd440294916 100644
--- a/test/freeflow/zeroeq/zeroeqtestproblem.hh
+++ b/test/freeflow/zeroeq/zeroeqtestproblem.hh
@@ -58,14 +58,10 @@ SET_TYPE_PROP(ZeroEqTestProblem, Grid, Dune::YaspGrid<2>);
 // Set the problem property
 SET_TYPE_PROP(ZeroEqTestProblem, Problem, Dumux::ZeroEqTestProblem<TypeTag>);
 
-// Set the fluids
-SET_PROP(ZeroEqTestProblem, Fluid)
-{
-private:
-    typedef typename GET_PROP_TYPE(TypeTag, Scalar) Scalar;
-public:
-    typedef Dumux::GasPhase<Scalar, Dumux::Air<Scalar> > type;
-};
+// Set the air as the gas phase
+SET_TYPE_PROP(ZeroEqTestProblem, Fluid,
+              Dumux::GasPhase<typename GET_PROP_TYPE(TypeTag, Scalar),
+                              Dumux::Air<typename GET_PROP_TYPE(TypeTag, Scalar)> >);
 
 // Disable gravity
 SET_BOOL_PROP(ZeroEqTestProblem, ProblemEnableGravity, false);
diff --git a/test/freeflow/zeroeq2c/test_zeroeq2c.cc b/test/freeflow/zeroeq2c/test_zeroeq2c.cc
index d9968d30b56fe01fb9533b09168ebfea50f4d2dc..0896870887ca746efef0d743d7fa69a54e4a46ca 100644
--- a/test/freeflow/zeroeq2c/test_zeroeq2c.cc
+++ b/test/freeflow/zeroeq2c/test_zeroeq2c.cc
@@ -59,6 +59,12 @@ void usage(const char *progName, const std::string &errorMsg)
 
 int main(int argc, char** argv)
 {
+#if (HAVE_SUPERLU || HAVE_UMFPACK)
     typedef TTAG(ZeroEq2cTestProblem) ProblemTypeTag;
     return Dumux::start<ProblemTypeTag>(argc, argv, usage);
+#else
+#warning "You need to have SuperLU or UMFPack installed to run this test."
+    std::cerr << "You need to have SuperLU or UMFPack installed to run this test\n";
+    return 77;
+#endif
 }
diff --git a/test/freeflow/zeroeq2c/zeroeq2ctestproblem.hh b/test/freeflow/zeroeq2c/zeroeq2ctestproblem.hh
index 226d58a1b09c37f000f29840ec63ef866de7d13d..12c3e695ee55713c3d6da69aeab87e81b7b01bda 100644
--- a/test/freeflow/zeroeq2c/zeroeq2ctestproblem.hh
+++ b/test/freeflow/zeroeq2c/zeroeq2ctestproblem.hh
@@ -56,13 +56,8 @@ SET_TYPE_PROP(ZeroEq2cTestProblem, Grid, Dune::YaspGrid<2>);
 SET_TYPE_PROP(ZeroEq2cTestProblem, Problem, Dumux::ZeroEq2cTestProblem<TypeTag>);
 
 // Select the fluid system
-SET_PROP(ZeroEq2cTestProblem, FluidSystem)
-{
-private:
-    typedef typename GET_PROP_TYPE(TypeTag, Scalar) Scalar;
-public:
-    typedef Dumux::FluidSystems::H2OAir<Scalar> type;
-};
+SET_TYPE_PROP(ZeroEq2cTestProblem, FluidSystem,
+              Dumux::FluidSystems::H2OAir<typename GET_PROP_TYPE(TypeTag, Scalar)>);
 
 // Disable gravity
 SET_BOOL_PROP(ZeroEq2cTestProblem, ProblemEnableGravity, false);
diff --git a/test/freeflow/zeroeq2cni/test_zeroeq2cni.cc b/test/freeflow/zeroeq2cni/test_zeroeq2cni.cc
index d53785b98cc08abe68fca9dd3520cc1e2f421895..c5caf316e53a4726d3c97f43747e5ff591c565c5 100644
--- a/test/freeflow/zeroeq2cni/test_zeroeq2cni.cc
+++ b/test/freeflow/zeroeq2cni/test_zeroeq2cni.cc
@@ -62,6 +62,12 @@ void usage(const char *progName, const std::string &errorMsg)
 
 int main(int argc, char** argv)
 {
+#if (HAVE_SUPERLU || HAVE_UMFPACK)
     typedef TTAG(ZeroEq2cniTestProblem) ProblemTypeTag;
     return Dumux::start<ProblemTypeTag>(argc, argv, usage);
+#else
+#warning "You need to have SuperLU or UMFPack installed to run this test."
+    std::cerr << "You need to have SuperLU or UMFPack installed to run this test\n";
+    return 77;
+#endif
 }
diff --git a/test/freeflow/zeroeq2cni/zeroeq2cnitestproblem.hh b/test/freeflow/zeroeq2cni/zeroeq2cnitestproblem.hh
index 678f782b11061e31cf8ba0470fd625fc4dcb2d05..f361151c67b210a7f09e9790707281acb8e56db7 100644
--- a/test/freeflow/zeroeq2cni/zeroeq2cnitestproblem.hh
+++ b/test/freeflow/zeroeq2cni/zeroeq2cnitestproblem.hh
@@ -56,13 +56,8 @@ SET_TYPE_PROP(ZeroEq2cniTestProblem, Grid, Dune::YaspGrid<2>);
 SET_TYPE_PROP(ZeroEq2cniTestProblem, Problem, Dumux::ZeroEq2cniTestProblem<TypeTag>);
 
 // Select the fluid system
-SET_PROP(ZeroEq2cniTestProblem, FluidSystem)
-{
-private:
-    typedef typename GET_PROP_TYPE(TypeTag, Scalar) Scalar;
-public:
-    typedef Dumux::FluidSystems::H2OAir<Scalar> type;
-};
+SET_TYPE_PROP(ZeroEq2cniTestProblem, FluidSystem,
+              Dumux::FluidSystems::H2OAir<typename GET_PROP_TYPE(TypeTag, Scalar)>);
 
 // Disable gravity
 SET_BOOL_PROP(ZeroEq2cniTestProblem, ProblemEnableGravity, false);