Fix some qml startup warnings

src/monitor/glwidget.cpp

@@ -130,7 +130,7 @@ GLWidget::GLWidget(int id, QObject *parent)
     m_blackClip->set("out", 3);
     connect(&m_refreshTimer, &QTimer::timeout, this, &GLWidget::refresh);
     m_producer = m_blackClip;
-
+    rootContext()->setContextProperty("markersModel", 0);
     if (!initGPUAccel()) {
         disableGPUAccel();
     }
@@ -956,6 +956,8 @@ int GLWidget::setProducer(const std::shared_ptr<Mlt::Producer> &producer, bool i
             removeAudioOverlay();
         }
         m_producer = m_blackClip;
+        // Reset markersModel
+        rootContext()->setContextProperty("markersModel", 0);
     }
     // redundant check. postcondition of above is m_producer != null
     if (m_producer) {

src/monitor/monitor.cpp

@@ -1353,7 +1353,6 @@ void Monitor::slotOpenClip(const std::shared_ptr<ProjectClip> &controller, int i
         disconnect(m_controller->getMarkerModel().get(), SIGNAL(rowsRemoved(const QModelIndex &, int, int)), this, SLOT(checkOverlay()));
     }
     m_controller = controller;
-    loadQmlScene(MonitorSceneDefault);
     m_snaps.reset(new SnapModel());
     m_glMonitor->getControllerProxy()->resetZone();
     if (controller) {
@@ -1367,6 +1366,7 @@ void Monitor::slotOpenClip(const std::shared_ptr<ProjectClip> &controller, int i
             return;
         }
         m_glMonitor->setRulerInfo((int)m_controller->frameDuration(), controller->getMarkerModel());
+        loadQmlScene(MonitorSceneDefault);
         m_timePos->setRange(0, (int)m_controller->frameDuration());
         updateMarkers();
         connect(m_glMonitor->getControllerProxy(), &MonitorProxy::addSnap, this, &Monitor::addSnapPoint, Qt::DirectConnection);
@@ -1389,6 +1389,7 @@ void Monitor::slotOpenClip(const std::shared_ptr<ProjectClip> &controller, int i
         m_glMonitor->getControllerProxy()->setClipHasAV(controller->hasAudioAndVideo());
         // hasEffects =  controller->hasEffects();
     } else {
+        loadQmlScene(MonitorSceneDefault);
         m_glMonitor->setProducer(nullptr, isActive());
         m_glMonitor->setAudioThumb();
         m_audioMeterWidget->audioChannels = 0;

src/monitor/qmlmanager.cpp

@@ -62,6 +62,8 @@ void QmlManager::setScene(Kdenlive::MonitorId id, MonitorSceneType type, QSize p
     }
     m_sceneType = type;
     QQuickItem *root = nullptr;
+    const QFont ft = QFontDatabase::systemFont(QFontDatabase::FixedFont);
+    m_view->rootContext()->setContextProperty("fixedFont", ft);
     switch (type) {
     case MonitorSceneGeometry:
         m_view->setSource(QUrl(QStringLiteral("qrc:/qml/kdenlivemonitoreffectscene.qml")));
@@ -117,8 +119,6 @@ void QmlManager::setScene(Kdenlive::MonitorId id, MonitorSceneType type, QSize p
     if (root && duration > 0) {
         root->setProperty("duration", duration);
     }
-    const QFont ft = QFontDatabase::systemFont(QFontDatabase::FixedFont);
-    m_view->rootContext()->setContextProperty("fixedFont", ft);
 }
 
 void QmlManager::effectRectChanged()