if no position was provided, negative pos

call the qml part with an invalid position if not supplied, will make new applets in the panels being put in the end instead of at the beginning

src/scriptengines/qml/plasmoid/containmentinterface.cpp

@@ -522,7 +522,7 @@ void ContainmentInterface::appletAddedForward(Plasma::Applet *applet)
     }
 
     m_appletInterfaces << appletGraphicObject;
-    emit appletAdded(appletGraphicObject, 0, 0);
+    emit appletAdded(appletGraphicObject, -1, -1);
     emit appletsChanged();
 }