Ensure internal effects like subtitles stay on top so that they are not...

Ensure internal effects like subtitles stay on top so that they are not affected by color or transform effects.
Fixes #1438

src/effects/effectstack/model/effectstackmodel.cpp

@@ -876,6 +876,24 @@ void EffectStackModel::registerItem(const std::shared_ptr<TreeItem> &item)
         if (!m_loadingExisting) {
             // qDebug() << "$$$$$$$$$$$$$$$$$$$$$ Planting effect in " << m_childServices.size();
             effectItem->plant(m_masterService);
+            // Check if we have an internal effect that needs to stay on top
+            if (m_ownerId.first == ObjectType::Master || m_ownerId.first == ObjectType::TimelineTrack) {
+                // check for subtitle effect
+                auto ms = m_masterService.lock();
+                int ct = ms->filter_count();
+                QVector <int> ixToMove;
+                for (int i = 0; i < ct; i++) {
+                    if (ms->filter(i)->get_int("internal_added") > 0) {
+                        ixToMove << i;
+                    }
+                }
+                std::sort(ixToMove.rbegin(), ixToMove.rend());
+                for (auto &ix : ixToMove) {
+                    if (ix < ct - 1) {
+                        ms->move_filter(ix, ct - 1);
+                    }
+                }
+            }
             for (const auto &service : m_childServices) {
                 // qDebug() << "$$$$$$$$$$$$$$$$$$$$$ Planting CLONE effect in " << (void *)service.lock().get();
                 effectItem->plantClone(service);