allow selective writing of child items

GUI/Model/Session/SessionItem.cpp

@@ -543,6 +543,11 @@ void SessionItem::writeNonSessionItems(QXmlStreamWriter*) const {}
 
 void SessionItem::readNonSessionItems(QXmlStreamReader*) {}
 
+bool SessionItem::allowWritingChildToXml(SessionItem* child) const
+{
+    return true;
+}
+
 void SessionItem::childDeleted(SessionItem* child)
 {
     int index = rowOfChild(child);

GUI/Model/Session/SessionItem.h

@@ -314,6 +314,7 @@ public:
 
     virtual void writeNonSessionItems(QXmlStreamWriter* writer) const;
     virtual void readNonSessionItems(QXmlStreamReader* reader);
+    virtual bool allowWritingChildToXml(SessionItem* child) const;
 
 private:
     void childDeleted(SessionItem* child);

GUI/Model/Session/SessionXML.cpp

@@ -82,7 +82,8 @@ void GUI::Session::XML::writeItemAndChildItems(QXmlStreamWriter* writer, const S
     }
 
     for (auto* child : item->children())
-        writeItemAndChildItems(writer, child);
+        if (item->allowWritingChildToXml(child))
+            writeItemAndChildItems(writer, child);
 
     QByteArray a = item->serializeBinaryData();
     if (!a.isEmpty()) {