diff --git a/playground/invoker/Invoker.cpp b/playground/invoker/Invoker.cpp
index 72105e65..83a60441 100644
--- a/playground/invoker/Invoker.cpp
+++ b/playground/invoker/Invoker.cpp
@@ -43,26 +43,26 @@ void Invoker::invoke( qreal realValue, int intValue,
     {
         void* args[4] = { nullptr };
 
-        const auto types = callback.invokable().parameterTypes();
+        void **a = args + 1;
+        const auto& invokable = callback.invokable();
 
-        int i = 1;
-        for ( auto type : types )
+        for ( int i = 0; i < invokable.parameterCount(); i++ )
         {
-            switch ( type )
+            switch ( invokable.parameterType( i ) )
             {
                 case QMetaType::Int:
                 {
-                    args[i++] = reinterpret_cast< void* >( &intValue );
+                    *a++ = reinterpret_cast< void* >( &intValue );
                     break;
                 }
                 case QMetaType::Double:
                 {
-                    args[i++] = reinterpret_cast< void* >( &realValue );
+                    *a++ = reinterpret_cast< void* >( &realValue );
                     break;
                 }
                 case QMetaType::QString:
                 {
-                    args[i++] = reinterpret_cast< void* >( &s );
+                    *a++ = reinterpret_cast< void* >( &s );
                     break;
                 }
                 default:
diff --git a/src/common/QskMetaInvokable.cpp b/src/common/QskMetaInvokable.cpp
index 7304e480..80761313 100644
--- a/src/common/QskMetaInvokable.cpp
+++ b/src/common/QskMetaInvokable.cpp
@@ -467,55 +467,55 @@ void QskMetaInvokable::reset()
     m_type = Invalid;
 }
 
-QVector< int > QskMetaInvokable::parameterTypes() const
+int QskMetaInvokable::parameterCount() const
 {
-    QVector< int > paramTypes;
-
     switch( m_type )
     {
         case MetaMethod:
         {
             // should be doable without QMetaMethod. TODO ...
             const auto method = QskMetaInvokable::method();
-
-            const int paramCount = method.parameterCount();
-            if ( paramCount > 0 )
-            {
-                paramTypes.reserve( paramCount );
-
-                for ( int i = 0; i < paramCount; i++ )
-                    paramTypes += method.parameterType( i );
-            }
-
-            break;
+            return method.parameterCount();
         }
         case MetaProperty:
         {
-            // should be doable without QMetaProperty. TODO ...
-            const auto property = QskMetaInvokable::property();
-            if ( property.isWritable() )
-            {
-                paramTypes.reserve( 1 );
-                paramTypes += property.userType();
-            }
-
-            break;
+            return 1;
         }
         case MetaFunction:
         {
-            auto types = function().parameterTypes();
-            if ( types )
-            {
-                while ( *types )
-                    paramTypes += *types++;
-            }
-            break;
+            return function().parameterCount();
         }
         default:
             break;
     }
 
-    return paramTypes;
+    return 0;
+}
+
+int QskMetaInvokable::parameterType( int index ) const
+{
+    switch( m_type )
+    {
+        case MetaMethod:
+        {
+            const auto method = QskMetaInvokable::method();
+            return method.parameterType( index );
+        }
+        case MetaProperty:
+        {
+            const auto property = QskMetaInvokable::property();
+            return property.userType();
+        }
+        case MetaFunction:
+        {
+            auto types = function().parameterTypes();
+            return types[index];
+        }
+        default:
+        {
+            return QMetaType::UnknownType;
+        }
+    }
 }
 
 int QskMetaInvokable::returnType() const
@@ -531,6 +531,9 @@ int QskMetaInvokable::returnType() const
             return function().returnType();
         }
         case MetaProperty:
+        {
+            return QMetaType::Void;
+        }
         default:
         {
             return QMetaType::Void;
@@ -560,7 +563,6 @@ QByteArray QskMetaInvokable::name() const
             return QByteArray();
         }
     }
-
 }
 
 QMetaMethod QskMetaInvokable::method() const
diff --git a/src/common/QskMetaInvokable.h b/src/common/QskMetaInvokable.h
index 320193a9..beff91ce 100644
--- a/src/common/QskMetaInvokable.h
+++ b/src/common/QskMetaInvokable.h
@@ -11,8 +11,6 @@
 #include <QMetaType>
 #include <Qt>
 
-template< typename T > class QVector;
-
 class QskMetaFunction;
 class QMetaObject;
 class QMetaMethod;
@@ -60,7 +58,9 @@ public:
     Type type() const;
     bool isNull() const;
 
-    QVector< int > parameterTypes() const;
+    int parameterCount() const;
+    int parameterType( int index ) const;
+
     int returnType() const;
 
     void invoke( QObject*, void* args[],
diff --git a/src/controls/QskShortcutMap.cpp b/src/controls/QskShortcutMap.cpp
index 69e9b0af..88b1b117 100644
--- a/src/controls/QskShortcutMap.cpp
+++ b/src/controls/QskShortcutMap.cpp
@@ -5,9 +5,9 @@
 
 #include "QskShortcutMap.h"
 #include "QskControl.h"
+#include "QskMetaInvokable.h"
 
 #include <QQuickWindow>
-#include <QMetaMethod>
 #include <QKeySequence>
 #include <QGlobalStatic>
 #include <QtGui/private/qguiapplication_p.h>
@@ -24,11 +24,8 @@ class QskShortcutHandler final : public QObject
 public:
     QskShortcutHandler();
 
-    int add( QQuickItem*, const QKeySequence&,
-        const QObject* receiver, const char* method );
-
-    int add( QQuickItem*, const QKeySequence&,
-        const QObject* receiver, QtPrivate::QSlotObjectBase* );
+    int insert( QQuickItem*, const QKeySequence&, bool autoRepeat,
+        const QObject*, const QskMetaInvokable& );
 
     void remove( int id );
 
@@ -38,8 +35,6 @@ public:
     virtual bool eventFilter( QObject*, QEvent* ) override final;
 
 private:
-    int insert( QQuickItem*, const QKeySequence&,
-        const QObject* receiver, const QMetaMethod&, QtPrivate::QSlotObjectBase* );
 
     void cleanUp( QObject* );
 
@@ -48,21 +43,13 @@ private:
     public:
         InvokeData():
             item( nullptr ),
-            receiver( nullptr ),
-            slotObject( nullptr )
+            receiver( nullptr )
         {
         }
 
-        ~InvokeData()
-        {
-            if ( slotObject )
-                slotObject->destroyIfLastRef();
-        }
-
         QQuickItem* item;
         const QObject* receiver;
-        QMetaMethod method;
-        QtPrivate::QSlotObjectBase* slotObject;
+        QskMetaInvokable invokable;
     };
 
     std::map< int, InvokeData > m_invokeDataMap;
@@ -82,7 +69,7 @@ static bool qskContextMatcher( QObject* object, Qt::ShortcutContext context )
         {
             /*
                 Unfortunatley there is no way to have to know about
-                the contextItem without making it the receiver of 
+                the contextItem without making it the receiver of
                 the following QShortcutEvent. So we have to install
                 an event handler to process and swallow it in QskShortcutHandler.
              */
@@ -101,39 +88,25 @@ QskShortcutHandler::QskShortcutHandler()
     installEventFilter( this );
 }
 
-int QskShortcutHandler::add( QQuickItem* item, const QKeySequence& sequence,
-    const QObject* receiver, const char* method )
+int QskShortcutHandler::insert(
+    QQuickItem* item, const QKeySequence& sequence, bool autoRepeat,
+    const QObject* receiver, const QskMetaInvokable& invokable )
 {
-    int id = 0;
-
-    if ( receiver )
+    if ( sequence.isEmpty() )
     {
-        const QMetaObject* metaObject = receiver->metaObject();
-
-        const int methodIndex = metaObject->indexOfMethod(
-            QMetaObject::normalizedSignature( method ).constData() + 1 );
-
-        if ( methodIndex >= 0 )
-        {
-            id = insert( item, sequence,
-                receiver, metaObject->method( methodIndex ), nullptr );
-        }
+        qDebug() << "QskShortcutMap: invalid shortcut key sequence";
+        return 0;
     }
 
-    return id;
-}
+#if 1
+    // should be a compile time check for functor based slots
+    if ( invokable.parameterCount() > 0 )
+    {
+        qDebug() << "QskShortcutMap: invalid slot parameter count";
+        return 0;
+    }
+#endif
 
-int QskShortcutHandler::add( QQuickItem* item, const QKeySequence& sequence,
-    const QObject* receiver, QtPrivate::QSlotObjectBase* slotObj )
-{
-    return insert( item, sequence, receiver, QMetaMethod(), slotObj );
-}
-
-int QskShortcutHandler::insert(
-    QQuickItem* item, const QKeySequence& sequence,
-    const QObject* receiver, const QMetaMethod& method,
-    QtPrivate::QSlotObjectBase* slotObject )
-{
     if ( receiver )
     {
         connect( receiver, &QObject::destroyed,
@@ -163,11 +136,10 @@ int QskShortcutHandler::insert(
 
     data.item = item;
     data.receiver = receiver;
+    data.invokable = invokable;
 
-    if ( slotObject )
-        data.slotObject = slotObject;
-    else
-        data.method = method;
+    if ( !autoRepeat )
+        setAutoRepeat( id, false );
 
     return id;
 }
@@ -266,30 +238,14 @@ bool QskShortcutHandler::eventFilter( QObject* object, QEvent* event )
     const auto it = m_invokeDataMap.find( se->shortcutId() );
     if ( it != m_invokeDataMap.end() )
     {
-        const auto& invokeData = it->second;
+        auto& data = it->second;
 
-        Q_ASSERT( invokeData.item == nullptr || invokeData.item == object );
+        Q_ASSERT( data.item == nullptr || data.item == object );
 
-        auto receiver = const_cast< QObject* >( invokeData.receiver );
+        auto receiver = const_cast< QObject* > ( data.receiver );
+        void* args[] = { nullptr };
 
-        if ( invokeData.slotObject )
-        {
-            void* args[] = { 0 };
-
-            if ( receiver && receiver->thread() != thread() )
-            {
-                QCoreApplication::postEvent( receiver,
-                    new QMetaCallEvent( invokeData.slotObject, nullptr, 0, 0, nullptr, args ) );
-            }
-            else
-            {
-                invokeData.slotObject->call( receiver, args );
-            }
-        }
-        else
-        {
-            invokeData.method.invoke( receiver, Qt::AutoConnection );
-        }
+        data.invokable.invoke( receiver, args, Qt::AutoConnection );
 
         return true;
     }
@@ -303,24 +259,26 @@ int QskShortcutMap::addMethod( QQuickItem* item, const QKeySequence& sequence,
 {
     if ( receiver == nullptr )
     {
+        qDebug() << "QskShortcutMap: bad receiver for shortcut:" << sequence;
         return 0;
     }
 
-    int id = qskShortcutHandler->add( item, sequence, receiver, method );
-    if ( id && !autoRepeat )
-        qskShortcutHandler->setAutoRepeat( id, false );
-
-    return id;
+    return qskShortcutHandler->insert(
+        item, sequence, autoRepeat, receiver, qskMetaMethod( receiver, method ) );
 }
 
-int QskShortcutMap::addSlotObject( QQuickItem* item, const QKeySequence& sequence,
-    bool autoRepeat, const QObject* receiver, QtPrivate::QSlotObjectBase* slotObject )
+int QskShortcutMap::addFunction( QQuickItem* item, const QKeySequence& sequence,
+    bool autoRepeat, const QObject* receiver, const QskMetaFunction& function )
 {
-    int id = qskShortcutHandler->add( item, sequence, receiver, slotObject );
-    if ( id && !autoRepeat )
-        qskShortcutHandler->setAutoRepeat( id, false );
+    if ( ( receiver == nullptr )
+        && ( function.functionType() == QskMetaFunction::Member ) )
+    {
+        qDebug() << "QskShortcutMap: bad receiver for shortcut:" << sequence;
+        return 0;
+    }
 
-    return id;
+    return qskShortcutHandler->insert(
+        item, sequence, autoRepeat, receiver, function );
 }
 
 void QskShortcutMap::setAutoRepeat( int id, bool on )
diff --git a/src/controls/QskShortcutMap.h b/src/controls/QskShortcutMap.h
index d6c5c569..fd4a611f 100644
--- a/src/controls/QskShortcutMap.h
+++ b/src/controls/QskShortcutMap.h
@@ -7,6 +7,8 @@
 #define QSK_SHORTCUT_MAP_H
 
 #include "QskGlobal.h"
+#include "QskMetaFunction.h"
+
 #include <QQuickWindow>
 
 class QQuickItem;
@@ -20,51 +22,34 @@ public:
 
     static void removeShortcut( int );
 
-    // -- traditional slots
-    static int addShortcut( const QKeySequence&, bool autoRepeat,
-        const QObject* receiver, const char* method );
+    // string based slots
+    static int addShortcut( const QKeySequence&,
+        bool autoRepeat, const QObject* receiver, const char* method );
 
-    static int addShortcut( QQuickWindow*, const QKeySequence&, bool autoRepeat,
-        const QObject* receiver, const char* method );
+    static int addShortcut( QQuickWindow*, const QKeySequence&,
+        bool autoRepeat, const QObject* receiver, const char* method );
 
-    static int addShortcut( QQuickItem*, const QKeySequence&, bool autoRepeat,
-        const QObject* receiver, const char* method );
+    static int addShortcut( QQuickItem*, const QKeySequence&,
+        bool autoRepeat, const QObject* receiver, const char* method );
 
-    // -- calling a QObject method
-    template< typename Func1 >
-    static int addShortcut( const QKeySequence&, bool autoRepeat,
-        const typename QtPrivate::FunctionPointer< Func1 >::Object* receiver, Func1 slot );
+    // functor based slots
+    static int addShortcut( const QKeySequence&,
+        bool autoRepeat, const QskMetaFunction& );
 
-    template< typename Func1 >
-    static int addShortcut( QQuickWindow*, const QKeySequence&, bool autoRepeat,
-        const typename QtPrivate::FunctionPointer< Func1 >::Object* receiver, Func1 slot );
+    static int addShortcut( const QKeySequence&,
+        bool autoRepeat, const QObject* context, const QskMetaFunction& );
 
-    template< typename Func1 >
-    static int addShortcut( QQuickItem*, const QKeySequence&, bool autoRepeat,
-        const typename QtPrivate::FunctionPointer< Func1 >::Object* receiver, Func1 slot );
+    static int addShortcut( QQuickItem*, const QKeySequence&,
+        bool autoRepeat, const QskMetaFunction& );
 
-    // -- calling a functor or function pointer inside a thread context
-    template< typename Func1 >
-    static int addShortcut( const QKeySequence&, bool autoRepeat,
-        const QObject* context, Func1 slot );
+    static int addShortcut( QQuickItem*, const QKeySequence&,
+        bool autoRepeat, const QObject* context, const QskMetaFunction& );
 
-    template< typename Func1 >
-    static int addShortcut( QQuickWindow*, const QKeySequence&, bool autoRepeat,
-        const QObject* context, Func1 slot );
+    static int addShortcut( QQuickWindow*, const QKeySequence&,
+        bool autoRepeat, const QskMetaFunction& );
 
-    template< typename Func1 >
-    static int addShortcut( QQuickItem*, const QKeySequence&, bool autoRepeat,
-        const QObject* context, Func1 slot );
-
-    // -- calling a functor or function pointer
-    template< typename Func1 >
-    static int addShortcut( const QKeySequence&, bool autoRepeat, Func1 slot );
-
-    template< typename Func1 >
-    static int addShortcut( QQuickWindow*, const QKeySequence&, bool autoRepeat, Func1 slot );
-
-    template< typename Func1 >
-    static int addShortcut( QQuickItem*, const QKeySequence&, bool autoRepeat, Func1 slot );
+    static int addShortcut( QQuickWindow*, const QKeySequence&,
+        bool autoRepeat, const QObject* context, const QskMetaFunction& );
 
     static bool contextMatcher( const QQuickItem*, Qt::ShortcutContext );
 
@@ -72,66 +57,15 @@ private:
     QskShortcutMap() = delete;
     ~QskShortcutMap() = delete;
 
-    static int addMethod( QQuickItem*, const QKeySequence&, bool autoRepeat,
-        const QObject* receiver, const char* method );
-
-    template< typename Func1 >
-    static int addMemberSlot( QQuickItem*, const QKeySequence&, bool autoRepeat,
-        const typename QtPrivate::FunctionPointer< Func1 >::Object* receiver, Func1 slot );
-
-    template< typename Func1 >
-    static int addFunctorSlot( QQuickItem*, const QKeySequence&,
-        bool autoRepeat, const QObject* context, Func1 slot );
-
-    static int addSlotObject(
+    static int addFunction(
         QQuickItem* item, const QKeySequence&, bool autoRepeat,
-        const QObject* receiver, QtPrivate::QSlotObjectBase* );
+        const QObject* receiver, const QskMetaFunction& );
+
+    static int addMethod(
+        QQuickItem* item, const QKeySequence&, bool autoRepeat,
+        const QObject* receiver, const char* );
 };
 
-template< typename Func1 >
-inline int QskShortcutMap::addMemberSlot(
-    QQuickItem* item, const QKeySequence& sequence, bool autoRepeat,
-    const typename QtPrivate::FunctionPointer< Func1 >::Object* receiver, Func1 slot )
-{
-    using namespace QtPrivate;
-    typedef FunctionPointer< Func1 > SlotType;
-
-    Q_STATIC_ASSERT_X( int( SlotType::ArgumentCount ) == 0,
-        "The slot must not have any arguments.");
-
-    return addSlotObject( item, sequence, autoRepeat, receiver, 
-        new QSlotObject< Func1, typename SlotType::Arguments, void >( slot ) );
-}
-
-template< typename Func1 >
-inline int QskShortcutMap::addFunctorSlot(
-    QQuickItem* item, const QKeySequence& sequence, bool autoRepeat,
-    const QObject* context, Func1 slot )
-{
-    using namespace QtPrivate;
-    typedef FunctionPointer< Func1 > SlotType;
-
-    Q_STATIC_ASSERT_X( int( SlotType::ArgumentCount ) <= 0,
-        "The slot must not have any arguments.");
-
-    Q_STATIC_ASSERT_X( !SlotType::IsPointerToMemberFunction,
-        "The slot must be no member function." );
-
-    using Args = List_Left< void, 0 >::Value;
-
-    return addSlotObject( item, sequence, autoRepeat, context, 
-        new QFunctorSlotObject< Func1, 0, Args, void >( slot ) );
-}
-
-// -- traditional slots
-
-inline int QskShortcutMap::addShortcut(
-    QQuickItem* item, const QKeySequence& sequence, bool autoRepeat,
-    const QObject* receiver, const char* method )
-{
-    return addMethod( item, sequence, autoRepeat, receiver, method );
-}
-
 inline int QskShortcutMap::addShortcut(
     const QKeySequence& sequence, bool autoRepeat,
     const QObject* receiver, const char* method )
@@ -140,89 +74,55 @@ inline int QskShortcutMap::addShortcut(
 }
 
 inline int QskShortcutMap::addShortcut(
-    QQuickWindow* window, const QKeySequence& sequence, bool autoRepeat,
-    const QObject* receiver, const char* method )
+    QQuickWindow* window, const QKeySequence& sequence,
+    bool autoRepeat, const QObject* receiver, const char* method )
 {
     auto item = window ? window->contentItem() : nullptr;
     return addMethod( item, sequence, autoRepeat, receiver, method );
 }
 
-// -- calling a QObject method
-
-template< typename Func1 >
-inline int QskShortcutMap::addShortcut(
-    QQuickItem* item, const QKeySequence& sequence, bool autoRepeat,
-    const typename QtPrivate::FunctionPointer< Func1 >::Object* receiver, Func1 slot )
-{
-    return addMemberSlot( item, sequence, autoRepeat, receiver, slot );
-}
-
-
-template< typename Func1 >
-inline int QskShortcutMap::addShortcut(
-    QQuickWindow* window, const QKeySequence& sequence, bool autoRepeat,
-    const typename QtPrivate::FunctionPointer< Func1 >::Object* receiver, Func1 slot )
-{
-    auto item = window ? window->contentItem() : nullptr;
-    return addMemberSlot( item, sequence, autoRepeat, receiver, slot );
-}
-
-template< typename Func1 >
 inline int QskShortcutMap::addShortcut(
     const QKeySequence& sequence, bool autoRepeat,
-    const typename QtPrivate::FunctionPointer< Func1 >::Object* receiver, Func1 slot )
+    const QskMetaFunction& function )
 {
-    return addMemberSlot( nullptr, sequence, autoRepeat, receiver, slot );
+    return addFunction( nullptr, sequence, autoRepeat, nullptr, function );
 }
 
-// -- calling a functor or function pointer with context
+inline int QskShortcutMap::addShortcut(
+    const QKeySequence& sequence, bool autoRepeat,
+    const QObject* context, const QskMetaFunction& function )
+{
+    return addFunction( nullptr, sequence, autoRepeat, context, function );
+}
 
-template< typename Func1 >
 inline int QskShortcutMap::addShortcut(
     QQuickItem* item, const QKeySequence& sequence, bool autoRepeat,
-    const QObject* context, Func1 slot )
+    const QskMetaFunction& function )
 {
-    return addFunctorSlot( item, sequence, autoRepeat, context, slot );
+    return addFunction( item, sequence, autoRepeat, nullptr, function );
+}
+
+inline int QskShortcutMap::addShortcut(
+    QQuickItem* item, const QKeySequence& sequence, bool autoRepeat,
+    const QObject* context, const QskMetaFunction& function )
+{
+    return addFunction( item, sequence, autoRepeat, context, function );
 }
 
-template< typename Func1 >
 inline int QskShortcutMap::addShortcut(
     QQuickWindow* window, const QKeySequence& sequence, bool autoRepeat,
-    const QObject* context, Func1 slot )
+    const QskMetaFunction& function )
 {
     auto item = window ? window->contentItem() : nullptr;
-    return addFunctorSlot( item, sequence, autoRepeat, context, slot );
+    return addFunction( item, sequence, autoRepeat, nullptr, function );
 }
 
-template< typename Func1 >
-inline int QskShortcutMap::addShortcut( const QKeySequence& sequence, bool autoRepeat,
-    const QObject* context, Func1 slot )
-{
-    return addFunctorSlot( nullptr, sequence, autoRepeat, context, slot );
-}
-
-// -- calling a functor or function pointer
-
-template< typename Func1 >
 inline int QskShortcutMap::addShortcut(
-    QQuickItem* item, const QKeySequence& sequence, bool autoRepeat, Func1 slot )
-{
-    return addFunctorSlot( item, sequence, autoRepeat, nullptr, slot );
-}
-
-template< typename Func1 >
-inline int QskShortcutMap::addShortcut(
-    QQuickWindow* window, const QKeySequence& sequence, bool autoRepeat, Func1 slot )
+    QQuickWindow* window, const QKeySequence& sequence, bool autoRepeat,
+    const QObject* context, const QskMetaFunction& function )
 {
     auto item = window ? window->contentItem() : nullptr;
-    return addFunctorSlot( item, sequence, autoRepeat, nullptr, autoRepeat, slot );
-}
-
-template< typename Func1 >
-int QskShortcutMap::addShortcut(
-    const QKeySequence& sequence, bool autoRepeat, Func1 slot )
-{
-    return addFunctorSlot( nullptr, sequence, autoRepeat, nullptr, slot );
+    return addFunction( item, sequence, autoRepeat, context, function );
 }
 
 #endif