diff --git a/generator/setupgenerator.cpp b/generator/setupgenerator.cpp
index c06fda3..4b33633 100644
--- a/generator/setupgenerator.cpp
+++ b/generator/setupgenerator.cpp
@@ -247,17 +247,21 @@ QStringList SetupGenerator::writePolymorphicHandler(QTextStream &s, const QStrin
     foreach (const AbstractMetaClass *clazz, allClasses) {
       bool inherits = false;
       if (isGraphicsItem) {
-        foreach(AbstractMetaClass* interfaze, clazz->interfaces()) {
-          if (interfaze->qualifiedCppName()=="QGraphicsItem") {
-            inherits = true;
-            break;
+        const AbstractMetaClass *currentClazz = clazz;
+        while (!inherits && currentClazz) {
+          foreach(AbstractMetaClass* interfaze, currentClazz->interfaces()) {
+            if (interfaze->qualifiedCppName()=="QGraphicsItem") {
+              inherits = true;
+              break;
+            }
           }
+          currentClazz = currentClazz->baseClass();
         }
       } else {
         inherits = clazz->inheritsFrom(cls);
       }
       if (clazz->package() == package && inherits) {
-        if (!clazz->typeEntry()->polymorphicIdValue().isEmpty() || isGraphicsItem) {
+        if (!clazz->typeEntry()->polymorphicIdValue().isEmpty()) {
           // On first find, open the function
           if (first) {
             first = false;
@@ -275,9 +279,6 @@ QStringList SetupGenerator::writePolymorphicHandler(QTextStream &s, const QStrin
 
           // For each, add case label
           QString polyId = clazz->typeEntry()->polymorphicIdValue();
-          if (isGraphicsItem) {
-            polyId = "%1->type() == " + clazz->qualifiedCppName() + "::Type";
-          }
           s << "    if ("
             << polyId.replace("%1", "object")
             << ") {" << endl
diff --git a/generator/typesystem_gui.xml b/generator/typesystem_gui.xml
index fbf67ba..5ae2920 100644
--- a/generator/typesystem_gui.xml
+++ b/generator/typesystem_gui.xml
@@ -1455,7 +1455,7 @@
   <interface-type name="QLayoutItem"/>
   <interface-type name="QPaintDevice"/>
 
-  <interface-type name="QGraphicsItem" delete-in-main-thread="yes">
+  <interface-type name="QGraphicsItem" delete-in-main-thread="yes" polymorphic-base="yes">
     <modify-function signature="setCursorForItemOnly(QCursor)" remove="all"/>
 
     <modify-function signature="setMatrix(QMatrix, bool)" remove="all"/>
@@ -1837,7 +1837,7 @@
     </modify-function>
   </object-type>
 
-  <object-type name="QGraphicsEllipseItem" delete-in-main-thread="yes"/>
+  <object-type name="QGraphicsEllipseItem" delete-in-main-thread="yes" polymorphic-id-expression="%1-&gt;type() == QGraphicsEllipseItem::Type" />
   <object-type name="QGraphicsItemAnimation">
     <modify-function signature="setItem(QGraphicsItem*)">
         <modify-argument index="1">
@@ -1854,29 +1854,30 @@
         <include file-name="QPair" location="global"/>
     </extra-includes>
   </object-type>
-  <object-type name="QGraphicsItemGroup" delete-in-main-thread="yes">
+  <object-type name="QGraphicsItemGroup" delete-in-main-thread="yes"
+  polymorphic-id-expression="%1-&gt;type() == QGraphicsItemGroup::Type">
       <modify-function signature="matrix()const" remove="all"/> <!--### Obsolete in 4.3-->
       <modify-function signature="resetMatrix()" remove="all"/> <!--### Obsolete in 4.3-->
       <modify-function signature="sceneMatrix()const" remove="all"/> <!--### Obsolete in 4.3-->
       <modify-function signature="setMatrix(QMatrix, bool)" remove="all"/> <!--### Obsolete in 4.3-->
   </object-type>
-  <object-type name="QGraphicsLineItem" delete-in-main-thread="yes">
+  <object-type name="QGraphicsLineItem" delete-in-main-thread="yes" polymorphic-id-expression="%1-&gt;type() == QGraphicsLineItem::Type">
       <modify-function signature="matrix()const" remove="all"/> <!--### Obsolete in 4.3-->
       <modify-function signature="resetMatrix()" remove="all"/> <!--### Obsolete in 4.3-->
       <modify-function signature="sceneMatrix()const" remove="all"/> <!--### Obsolete in 4.3-->
       <modify-function signature="setMatrix(QMatrix, bool)" remove="all"/> <!--### Obsolete in 4.3-->
   </object-type>
-  <object-type name="QGraphicsPathItem" delete-in-main-thread="yes"/>
+  <object-type name="QGraphicsPathItem" delete-in-main-thread="yes" polymorphic-id-expression="%1-&gt;type() == QGraphicsPathItem::Type"/>
 
-  <object-type name="QGraphicsPixmapItem" delete-in-main-thread="yes">
+  <object-type name="QGraphicsPixmapItem" delete-in-main-thread="yes" polymorphic-id-expression="%1-&gt;type() == QGraphicsPixmapItem::Type">
       <modify-function signature="matrix()const" remove="all"/> <!--### Obsolete in 4.3-->
       <modify-function signature="resetMatrix()" remove="all"/> <!--### Obsolete in 4.3-->
       <modify-function signature="sceneMatrix()const" remove="all"/> <!--### Obsolete in 4.3-->
       <modify-function signature="setMatrix(QMatrix, bool)" remove="all"/> <!--### Obsolete in 4.3-->
   </object-type>
-  <object-type name="QGraphicsPolygonItem" delete-in-main-thread="yes"/>
-  <object-type name="QGraphicsRectItem" delete-in-main-thread="yes"/>
-  <object-type name="QGraphicsSimpleTextItem" delete-in-main-thread="yes"/>
+  <object-type name="QGraphicsPolygonItem" delete-in-main-thread="yes" polymorphic-id-expression="%1-&gt;type() == QGraphicsPolygonItem::Type"/>
+  <object-type name="QGraphicsRectItem" delete-in-main-thread="yes" polymorphic-id-expression="%1-&gt;type() == QGraphicsRectItem::Type"/>
+  <object-type name="QGraphicsSimpleTextItem" delete-in-main-thread="yes" polymorphic-id-expression="%1-&gt;type() == QGraphicsSimpleTextItem::Type"/>
   <object-type name="QHBoxLayout"/>
   <object-type name="QHeaderView">
     <modify-function signature="initStyleOption(QStyleOptionHeader*)const">
@@ -3518,7 +3519,7 @@
     <modify-function signature="operator&lt;(QListWidgetItem)const" remove="all"/>
   </object-type>
 
-  <object-type name="QGraphicsTextItem"> <!-- a QObject so main-thread delete redundant -->
+  <object-type name="QGraphicsTextItem" polymorphic-id-expression="%1-&gt;type() == QGraphicsTextItem::Type"> <!-- a QObject so main-thread delete redundant -->
     <extra-includes>
       <include file-name="QTextCursor" location="global"/>
     </extra-includes>
@@ -5427,7 +5428,9 @@
     </modify-function>
   </object-type>
   <object-type name="QGraphicsProxyWidget"/> <!-- a QObject so main-thread delete redundant -->
-  <object-type name="QGraphicsWidget">  <!-- a QObject so main-thread delete redundant -->
+  <object-type name="QGraphicsWidget"
+    polymorphic-id-expression="%1-&gt;isWidget()">
+    <!-- a QObject so main-thread delete redundant -->
     <!-- Duplicate function to QObject::children() to override accidental shadowing which is not present in Jambi -->
     <modify-function signature="children()const" remove="all"/>
     <modify-function signature="setLayout(QGraphicsLayout*)">