diff --git a/src/gsi/gsi/gsiClass.h b/src/gsi/gsi/gsiClass.h
index edad9e75d..e116d54bb 100644
--- a/src/gsi/gsi/gsiClass.h
+++ b/src/gsi/gsi/gsiClass.h
@@ -30,6 +30,7 @@
 #include "tlTypeTraits.h"
 #include "tlHeap.h"
 #include "tlUtils.h"
+#include "tlVariant.h"
 
 #include <memory>
 
@@ -76,7 +77,7 @@ struct _var_user_less_impl<T, false>
 };
 
 /**
- *  @brief A helper function to implement equal as efficiently as possible
+ *  @brief A helper function to implement to_string as efficiently as possible
  */
 template<class T, bool> struct _var_user_to_string_impl;
 
@@ -92,6 +93,57 @@ struct _var_user_to_string_impl<T, false>
   static std::string call (const T *a, const VariantUserClassImpl *delegate) { return delegate->to_string_impl ((void *) a); }
 };
 
+/**
+ *  @brief A helper function to implement to_variant as efficiently as possible
+ */
+template<class T, bool> struct _var_user_to_variant_impl;
+
+template<class T>
+struct _var_user_to_variant_impl<T, true>
+{
+  static tl::Variant call (const T *a, const VariantUserClassImpl * /*delegate*/) { return a->to_variant (); }
+};
+
+template<class T>
+struct _var_user_to_variant_impl<T, false>
+{
+  static tl::Variant call (const T *a, const VariantUserClassImpl *delegate) { return delegate->to_variant_impl ((void *) a); }
+};
+
+/**
+ *  @brief A helper function to implement to_int as efficiently as possible
+ */
+template<class T, bool> struct _var_user_to_int_impl;
+
+template<class T>
+struct _var_user_to_int_impl<T, true>
+{
+  static int call (const T *a, const VariantUserClassImpl * /*delegate*/) { return a->to_int (); }
+};
+
+template<class T>
+struct _var_user_to_int_impl<T, false>
+{
+  static int call (const T *a, const VariantUserClassImpl *delegate) { return delegate->to_int_impl ((void *) a); }
+};
+
+/**
+ *  @brief A helper function to implement to_double as efficiently as possible
+ */
+template<class T, bool> struct _var_user_to_double_impl;
+
+template<class T>
+struct _var_user_to_double_impl<T, true>
+{
+  static double call (const T *a, const VariantUserClassImpl * /*delegate*/) { return a->to_double (); }
+};
+
+template<class T>
+struct _var_user_to_double_impl<T, false>
+{
+  static double call (const T *a, const VariantUserClassImpl *delegate) { return delegate->to_double_impl ((void *) a); }
+};
+
 /**
  *  @brief A VariantUserClassBase specialization that links GSI classes and Variant classes
  */
@@ -152,11 +204,26 @@ public:
     return gsi::_var_user_less_impl<T, tl::has_less_operator<T>::value>::call ((const T *) a, (const T *) b, this);
   }
 
+  virtual void to_variant (const void *a, tl::Variant &var) const
+  {
+    var = gsi::_var_user_to_variant_impl<T, tl::has_to_variant<T>::value>::call ((const T *) a, this);
+  }
+
   virtual std::string to_string (const void *a) const
   {
     return gsi::_var_user_to_string_impl<T, tl::has_to_string<T>::value>::call ((const T *) a, this);
   }
 
+  virtual int to_int (const void *a) const
+  {
+    return gsi::_var_user_to_int_impl<T, tl::has_to_int<T>::value>::call ((const T *) a, this);
+  }
+
+  virtual double to_double (const void *a) const
+  {
+    return gsi::_var_user_to_double_impl<T, tl::has_to_double<T>::value>::call ((const T *) a, this);
+  }
+
   void *clone (const void *obj) const
   {
     void *new_obj = mp_cls->create ();
diff --git a/src/gsi/gsi/gsiEnums.h b/src/gsi/gsi/gsiEnums.h
index acbee7079..457bb305a 100644
--- a/src/gsi/gsi/gsiEnums.h
+++ b/src/gsi/gsi/gsiEnums.h
@@ -26,6 +26,7 @@
 
 #include "gsiDecl.h"
 #include "tlString.h"
+#include "tlVariant.h"
 
 #if defined(HAVE_QT)
 #  include <QFlags>
@@ -60,6 +61,16 @@ public:
   E &value () { return m_e; }
   const E &value () const { return m_e; }
 
+  int to_int () const { return int (m_e); }
+  tl::Variant to_variant () const { return tl::Variant (int (m_e)); }
+
+  std::string to_string () const
+  {
+    const Enum<E> *ecls = dynamic_cast<const Enum<E> *> (cls_decl<E> ());
+    tl_assert (ecls != 0);
+    return ecls->enum_to_string (m_e);
+  }
+
 private:
   E m_e;
 };
@@ -209,7 +220,7 @@ public:
     return ecls->enum_to_string_inspect (*e);
   }
 
-  static int enum_to_i (const E *e) 
+  static int enum_to_int (const E *e)
   {
     return int (*e); 
   }
@@ -219,16 +230,31 @@ public:
     return *e == other;
   }
 
-  static bool enum_ne (const E *e, const E &other) 
+  static bool enum_eq_with_int (const E *e, int other)
+  {
+    return int (*e) == other;
+  }
+
+  static bool enum_ne (const E *e, const E &other)
   {
     return *e != other;
   }
 
-  static bool enum_lt (const E *e, const E &other) 
+  static bool enum_ne_with_int (const E *e, int other)
+  {
+    return int (*e) != other;
+  }
+
+  static bool enum_lt (const E *e, const E &other)
   {
     return *e < other;
   }
 
+  static bool enum_lt_with_int (const E *e, int other)
+  {
+    return int (*e) < other;
+  }
+
   static E *new_enum_from_int (int i)
   {
     return new E (E (i));
@@ -248,10 +274,13 @@ public:
       gsi::constructor ("new", &new_enum_from_string, gsi::arg("s"), "@brief Creates an enum from a string value") +
       gsi::method_ext ("to_s", &enum_to_string_ext, "@brief Gets the symbolic string from an enum") +
       gsi::method_ext ("inspect", &enum_to_string_inspect_ext, "@brief Converts an enum to a visual string") +
-      gsi::method_ext ("to_i", &enum_to_i, "@brief Gets the integer value from the enum") +
+      gsi::method_ext ("to_i", &enum_to_int, "@brief Gets the integer value from the enum") +
       gsi::method_ext ("==", &enum_eq, gsi::arg("other"), "@brief Compares two enums") +
+      gsi::method_ext ("==", &enum_eq_with_int, gsi::arg("other"), "@brief Compares an enum with an integer value") +
       gsi::method_ext ("!=", &enum_ne, gsi::arg("other"), "@brief Compares two enums for inequality") +
-      gsi::method_ext ("<", &enum_lt, gsi::arg("other"), "@brief Returns true if the first enum is less (in the enum symbol order) than the second");
+      gsi::method_ext ("!=", &enum_ne_with_int, gsi::arg("other"), "@brief Compares an enum with an integer for inequality") +
+      gsi::method_ext ("<", &enum_lt, gsi::arg("other"), "@brief Returns true if the first enum is less (in the enum symbol order) than the second") +
+      gsi::method_ext ("<", &enum_lt_with_int, gsi::arg("other"), "@brief Returns true if the enum is less (in the enum symbol order) than the integer value");
 
     return m + defs ();
   }
diff --git a/src/gsi/gsi/gsiExpression.cc b/src/gsi/gsi/gsiExpression.cc
index b6e534342..abda57030 100644
--- a/src/gsi/gsi/gsiExpression.cc
+++ b/src/gsi/gsi/gsiExpression.cc
@@ -1241,6 +1241,96 @@ VariantUserClassImpl::to_string_impl (void *obj) const
   }
 }
 
+tl::Variant
+VariantUserClassImpl::to_variant_impl (void *obj) const
+{
+  if (obj) {
+
+    if (! has_method ("to_v")) {
+
+      //  no method to convert the object to a string
+      return tl::Variant ();
+
+    } else {
+
+      tl::ExpressionParserContext context;
+
+      tl::Variant out;
+
+      tl::Variant object (obj, mp_object_cls, false);
+      std::vector<tl::Variant> vv;
+
+      execute_gsi (context, out, object, "to_v", vv);
+
+      return out;
+
+    }
+
+  } else {
+    return tl::Variant ();
+  }
+}
+
+int
+VariantUserClassImpl::to_int_impl (void *obj) const
+{
+  if (obj) {
+
+    if (! has_method ("to_i")) {
+
+      //  no method to convert the object to an integer
+      return 0;
+
+    } else {
+
+      tl::ExpressionParserContext context;
+
+      tl::Variant out;
+
+      tl::Variant object (obj, mp_object_cls, false);
+      std::vector<tl::Variant> vv;
+
+      execute_gsi (context, out, object, "to_i", vv);
+
+      return out.to_int ();
+
+    }
+
+  } else {
+    return 0;
+  }
+}
+
+double
+VariantUserClassImpl::to_double_impl (void *obj) const
+{
+  if (obj) {
+
+    if (! has_method ("to_f")) {
+
+      //  no method to convert the object to a double value
+      return 0.0;
+
+    } else {
+
+      tl::ExpressionParserContext context;
+
+      tl::Variant out;
+
+      tl::Variant object (obj, mp_object_cls, false);
+      std::vector<tl::Variant> vv;
+
+      execute_gsi (context, out, object, "to_f", vv);
+
+      return out.to_double ();
+
+    }
+
+  } else {
+    return 0.0;
+  }
+}
+
 void
 VariantUserClassImpl::execute (const tl::ExpressionParserContext &context, tl::Variant &out, tl::Variant &object, const std::string &method, const std::vector<tl::Variant> &args) const
 {
diff --git a/src/gsi/gsi/gsiExpression.h b/src/gsi/gsi/gsiExpression.h
index d422999d9..d0ff096d4 100644
--- a/src/gsi/gsi/gsiExpression.h
+++ b/src/gsi/gsi/gsiExpression.h
@@ -50,7 +50,10 @@ public:
 
   bool equal_impl (void *, void *) const;
   bool less_impl (void *, void *) const;
+  tl::Variant to_variant_impl (void *) const;
   std::string to_string_impl (void *) const;
+  int to_int_impl (void *) const;
+  double to_double_impl (void *) const;
 
   virtual void execute (const tl::ExpressionParserContext &context, tl::Variant &out, tl::Variant &object, const std::string &method, const std::vector<tl::Variant> &args) const;
 
diff --git a/src/laybasic/laybasic/gsiDeclLayLayoutView.cc b/src/laybasic/laybasic/gsiDeclLayLayoutView.cc
index 856e44fbb..e5bf11472 100644
--- a/src/laybasic/laybasic/gsiDeclLayLayoutView.cc
+++ b/src/laybasic/laybasic/gsiDeclLayLayoutView.cc
@@ -1984,6 +1984,9 @@ static std::string get_technology (const lay::CellViewRef *cv)
 
 static tl::Event &get_technology_changed_event (lay::CellViewRef *cv)
 {
+  if (! cv->is_valid ()) {
+    throw tl::Exception (tl::to_string (QObject::tr ("Not a valid cellview")));
+  }
   return (*cv)->technology_changed_event;
 }
 
diff --git a/src/pya/pya/pyaModule.cc b/src/pya/pya/pyaModule.cc
index 54f81d9e5..0f962fa7e 100644
--- a/src/pya/pya/pyaModule.cc
+++ b/src/pya/pya/pyaModule.cc
@@ -632,6 +632,14 @@ static std::string extract_python_name (const std::string &name)
 static void
 pya_object_deallocate (PyObject *self)
 {
+  //  This avoids an assertion in debug builds (Python, gcmodule.c - update_refs).
+  //  In short, the GC expects not to see objects with refcount 0 and asserts.
+  //  However, due to triggering of signals or similar, the destructor call below
+  //  may trigger a GC (https://github.com/KLayout/klayout/issues/1054).
+  //  According to the comments this may be turned into a release mode assertion, so
+  //  we better work around it.
+  ++self->ob_refcnt;
+
   PYAObjectBase *p = PYAObjectBase::from_pyobject (self);
   p->~PYAObjectBase ();
   Py_TYPE (self)->tp_free (self);
diff --git a/src/tl/tl/tlTypeTraits.h b/src/tl/tl/tlTypeTraits.h
index 9f94978f6..491907dc5 100644
--- a/src/tl/tl/tlTypeTraits.h
+++ b/src/tl/tl/tlTypeTraits.h
@@ -71,6 +71,18 @@ inline bool value_of (false_tag) { return false; }
 typedef char __yes_type [1];
 typedef char __no_type [2];
 
+/**
+ *  @brief Detects whether a class has a "to_variant" method with a matching signature
+ */
+template <typename T> static __yes_type &__test_to_variant_func (decltype (&T::to_variant));
+template <typename> static __no_type &__test_to_variant_func (...);
+
+template <typename T>
+struct has_to_variant
+{
+  static constexpr bool value = sizeof (__test_to_variant_func<T> (nullptr)) == sizeof (__yes_type);
+};
+
 /**
  *  @brief Detects whether a class has a "to_string" method with a matching signature
  */
@@ -83,6 +95,30 @@ struct has_to_string
   static constexpr bool value = sizeof (__test_to_string_func<T> (nullptr)) == sizeof (__yes_type);
 };
 
+/**
+ *  @brief Detects whether a class has a "to_int" method with a matching signature
+ */
+template <typename T> static __yes_type &__test_to_int_func (decltype (&T::to_int));
+template <typename> static __no_type &__test_to_int_func (...);
+
+template <typename T>
+struct has_to_int
+{
+  static constexpr bool value = sizeof (__test_to_int_func<T> (nullptr)) == sizeof (__yes_type);
+};
+
+/**
+ *  @brief Detects whether a class has a "to_double" method with a matching signature
+ */
+template <typename T> static __yes_type &__test_to_double_func (decltype (&T::to_double));
+template <typename> static __no_type &__test_to_double_func (...);
+
+template <typename T>
+struct has_to_double
+{
+  static constexpr bool value = sizeof (__test_to_double_func<T> (nullptr)) == sizeof (__yes_type);
+};
+
 /**
  *  @brief Detects whether a class has an equal operator
  */
diff --git a/src/tl/tl/tlVariant.cc b/src/tl/tl/tlVariant.cc
index 72dd3c32d..7e46e0add 100644
--- a/src/tl/tl/tlVariant.cc
+++ b/src/tl/tl/tlVariant.cc
@@ -1820,6 +1820,10 @@ Variant::to_int128 () const
     __int128 l = 0;
     ex.read (l);
     return l;
+  } else if (m_type == t_user) {
+    return m_var.mp_user.cls->to_int (m_var.mp_user.object);
+  } else if (m_type == t_user_ref) {
+    return m_var.mp_user_ref.cls->to_int (m_var.mp_user_ref.cls->deref_proxy_const (reinterpret_cast <const tl::WeakOrSharedPtr *> (m_var.mp_user_ref.ptr)->get ()));
   } else {
     return 0;
   }
@@ -1875,6 +1879,10 @@ Variant::to_ulonglong () const
     unsigned long long l = 0;
     tl::from_string (to_string (), l);
     return l;
+  } else if (m_type == t_user) {
+    return (unsigned long long) m_var.mp_user.cls->to_int (m_var.mp_user.object);
+  } else if (m_type == t_user_ref) {
+    return (unsigned long long) m_var.mp_user_ref.cls->to_int (m_var.mp_user_ref.cls->deref_proxy_const (reinterpret_cast <const tl::WeakOrSharedPtr *> (m_var.mp_user_ref.ptr)->get ()));
   } else {
     return 0;
   }
@@ -1929,6 +1937,10 @@ Variant::to_longlong () const
     long long l = 0;
     tl::from_string (to_string (), l);
     return l;
+  } else if (m_type == t_user) {
+    return (long long) m_var.mp_user.cls->to_int (m_var.mp_user.object);
+  } else if (m_type == t_user_ref) {
+    return (long long) m_var.mp_user_ref.cls->to_int (m_var.mp_user_ref.cls->deref_proxy_const (reinterpret_cast <const tl::WeakOrSharedPtr *> (m_var.mp_user_ref.ptr)->get ()));
   } else {
     return 0;
   }
@@ -1983,6 +1995,10 @@ Variant::to_ulong () const
     unsigned long l = 0;
     tl::from_string (to_string (), l);
     return l;
+  } else if (m_type == t_user) {
+    return (unsigned long) m_var.mp_user.cls->to_int (m_var.mp_user.object);
+  } else if (m_type == t_user_ref) {
+    return (unsigned long) m_var.mp_user_ref.cls->to_int (m_var.mp_user_ref.cls->deref_proxy_const (reinterpret_cast <const tl::WeakOrSharedPtr *> (m_var.mp_user_ref.ptr)->get ()));
   } else {
     return 0;
   }
@@ -2037,6 +2053,10 @@ Variant::to_long () const
     long l = 0;
     tl::from_string (to_string (), l);
     return l;
+  } else if (m_type == t_user) {
+    return (long) m_var.mp_user.cls->to_int (m_var.mp_user.object);
+  } else if (m_type == t_user_ref) {
+    return (long) m_var.mp_user_ref.cls->to_int (m_var.mp_user_ref.cls->deref_proxy_const (reinterpret_cast <const tl::WeakOrSharedPtr *> (m_var.mp_user_ref.ptr)->get ()));
   } else {
     return 0;
   }
@@ -2143,6 +2163,10 @@ Variant::to_double () const
     double d = 0;
     tl::from_string (to_string (), d);
     return d;
+  } else if (m_type == t_user) {
+    return m_var.mp_user.cls->to_double (m_var.mp_user.object);
+  } else if (m_type == t_user_ref) {
+    return m_var.mp_user_ref.cls->to_double (m_var.mp_user_ref.cls->deref_proxy_const (reinterpret_cast <const tl::WeakOrSharedPtr *> (m_var.mp_user_ref.ptr)->get ()));
   } else {
     return 0;
   }
@@ -2513,7 +2537,9 @@ QVariant Variant::to_qvariant () const
       } else if (dynamic_cast<const tl::VariantUserClass<QVector4D> *> (cls)) {
         return QVariant (to_user<QVector4D> ());
       } else {
-        return QVariant ();
+        tl::Variant var;
+        cls->to_variant (to_user (), var);
+        return var.to_qvariant ();
       }
     }
   default:
diff --git a/src/tl/tl/tlVariant.h b/src/tl/tl/tlVariant.h
index d50b33be5..14a388dea 100644
--- a/src/tl/tl/tlVariant.h
+++ b/src/tl/tl/tlVariant.h
@@ -53,6 +53,7 @@ namespace gsi
 namespace tl
 {
 
+class Variant;
 class Extractor;
 class EvalClass;
 template <class T> void extractor_impl (tl::Extractor &, T &);
@@ -76,6 +77,9 @@ public:
   virtual bool less (const void *, const void *) const = 0;
   virtual void *clone (const void *) const = 0;
   virtual std::string to_string (const void *) const = 0;
+  virtual int to_int (const void *) const = 0;
+  virtual double to_double (const void *) const = 0;
+  virtual void to_variant (const void *, tl::Variant &var) const = 0;
   virtual void read (void *, tl::Extractor &ex) const = 0;
   virtual const char *name () const = 0;
   virtual bool is_const () const = 0;
diff --git a/src/tl/tl/tlVariantUserClasses.h b/src/tl/tl/tlVariantUserClasses.h
index 4596eac5e..db27a852c 100644
--- a/src/tl/tl/tlVariantUserClasses.h
+++ b/src/tl/tl/tlVariantUserClasses.h
@@ -119,6 +119,57 @@ struct _var_user_to_string_impl<T, false>
   static std::string call (const T *) { tl_assert (false); }
 };
 
+/**
+ *  @brief A helper function to implement equal as efficiently as possible
+ */
+template<class T, bool> struct _var_user_to_int_impl;
+
+template<class T>
+struct _var_user_to_int_impl<T, true>
+{
+  static int call (const T *a) { return a->to_int (); }
+};
+
+template<class T>
+struct _var_user_to_int_impl<T, false>
+{
+  static int call (const T *) { tl_assert (false); }
+};
+
+/**
+ *  @brief A helper function to implement equal as efficiently as possible
+ */
+template<class T, bool> struct _var_user_to_double_impl;
+
+template<class T>
+struct _var_user_to_double_impl<T, true>
+{
+  static double call (const T *a) { return a->to_double (); }
+};
+
+template<class T>
+struct _var_user_to_double_impl<T, false>
+{
+  static double call (const T *) { tl_assert (false); }
+};
+
+/**
+ *  @brief A helper function to implement equal as efficiently as possible
+ */
+template<class T, bool> struct _var_user_to_variant_impl;
+
+template<class T>
+struct _var_user_to_variant_impl<T, true>
+{
+  static tl::Variant call (const T *a) { return a->to_variant (); }
+};
+
+template<class T>
+struct _var_user_to_variant_impl<T, false>
+{
+  static tl::Variant call (const T *) { tl_assert (false); }
+};
+
 /**
  *  @brief A utility implementation of tl::VariantUserClass using type traits for the implementation
  */
@@ -162,7 +213,22 @@ public:
     return _var_user_to_string_impl<T, tl::has_to_string<T>::value>::call ((const T *) a);
   }
 
-  virtual void read (void *a, tl::Extractor &ex) const 
+  virtual int to_int (const void *a) const
+  {
+    return _var_user_to_int_impl<T, tl::has_to_int<T>::value>::call ((const T *) a);
+  }
+
+  virtual double to_double (const void *a) const
+  {
+    return _var_user_to_double_impl<T, tl::has_to_double<T>::value>::call ((const T *) a);
+  }
+
+  virtual void to_variant (const void *a, tl::Variant &v) const
+  {
+    v = _var_user_to_variant_impl<T, tl::has_to_variant<T>::value>::call ((const T *) a);
+  }
+
+  virtual void read (void *a, tl::Extractor &ex) const
   { 
     ex.read (*(T *)a);
   }
diff --git a/src/tl/unit_tests/tlExpressionTests.cc b/src/tl/unit_tests/tlExpressionTests.cc
index 6cd4fb4c0..b25c54c44 100644
--- a/src/tl/unit_tests/tlExpressionTests.cc
+++ b/src/tl/unit_tests/tlExpressionTests.cc
@@ -454,6 +454,9 @@ public:
   virtual void *clone (const void *) const { tl_assert (false); }
   virtual void assign (void *, const void *) const { tl_assert (false); }
   virtual std::string to_string (const void *) const { tl_assert (false); }
+  virtual int to_int (const void *) const { tl_assert (false); }
+  virtual double to_double (const void *) const { tl_assert (false); }
+  virtual void to_variant (const void *, tl::Variant &) const { tl_assert (false); }
   virtual void read (void *, tl::Extractor &) const { }
   virtual const char *name () const { return "Box"; }
   virtual unsigned int type_code () const { return 0; }
@@ -519,6 +522,9 @@ public:
   virtual void *clone (const void *) const { tl_assert (false); }
   virtual void assign (void *, const void *) const { tl_assert (false); }
   virtual std::string to_string (const void *) const { tl_assert (false); }
+  virtual int to_int (const void *) const { tl_assert (false); }
+  virtual double to_double (const void *) const { tl_assert (false); }
+  virtual void to_variant (const void *, tl::Variant &) const { tl_assert (false); }
   virtual void read (void *, tl::Extractor &) const { }
   virtual const char *name () const { return "Edge"; }
   virtual unsigned int type_code () const { return 0; }