Setter for Modified attribute

src/Gui/DocumentPy.xml

@@ -237,7 +237,7 @@ obj : Gui.ViewProvider</UserDocu>
       </Documentation>
       <Parameter Name="Transacting" Type="Boolean" />
     </Attribute>
-    <Attribute Name="Modified" ReadOnly="true">
+    <Attribute Name="Modified">
       <Documentation>
         <UserDocu>Returns True if the document is marked as modified, and False otherwise.</UserDocu>
       </Documentation>

src/Gui/DocumentPyImp.cpp

@@ -504,6 +504,11 @@ Py::Boolean DocumentPy::getModified() const
     return {getDocumentPtr()->isModified()};
 }
 
+void DocumentPy::setModified(Py::Boolean arg)
+{
+    getDocumentPtr()->setModified(arg);
+}
+
 PyObject *DocumentPy::getCustomAttributes(const char* attr) const
 {
     // Note: Here we want to return only a document object if its