added buttons to drag just video or just audio

panels/panels.cpp

@@ -87,6 +87,7 @@ void alloc_panels(QWidget* parent) {
   panel_sequence_viewer->setObjectName("seq_viewer");
   panel_footage_viewer = new Viewer(parent);
   panel_footage_viewer->setObjectName("footage_viewer");
+  panel_footage_viewer->show_videoaudio_buttons(true);
   panel_project = new Project(parent);
   panel_project->setObjectName("proj_root");
   panel_effect_controls = new EffectControls(parent);