mainwindow: set unique object name on all panels that are in a "series"

app/window/mainwindow/mainwindow.cpp

@@ -180,6 +180,11 @@ void MainWindow::FolderOpen(Project *p, Item *i, bool floating)
 {
   ProjectPanel* panel = PanelManager::instance()->CreatePanel<ProjectPanel>(this);
 
+  // Set custom name to distinguish it from regular ProjectPanels
+  panel->setObjectName(QStringLiteral("FolderPanel"));
+
+  SetUniquePanelID<ProjectPanel>(panel, folder_panels_);
+
   panel->set_project(p);
   panel->set_root(i);
 
@@ -508,6 +513,8 @@ T *MainWindow::AppendPanelInternal(QList<T*>& list)
 {
   T* panel = PanelManager::instance()->CreatePanel<T>(this);
 
+  SetUniquePanelID(panel, list);
+
   if (!list.isEmpty()) {
     tabifyDockWidget(list.last(), panel);
   }
@@ -524,4 +531,11 @@ T *MainWindow::AppendPanelInternal(QList<T*>& list)
   return panel;
 }
 
+template<typename T>
+void MainWindow::SetUniquePanelID(T *panel, const QList<T *> &list)
+{
+  // Set unique object name so it can be identified by QMainWindow's save and restore state functions
+  panel->setObjectName(panel->objectName().append(QString::number(list.size())));
+}
+
 OLIVE_NAMESPACE_EXIT

app/window/mainwindow/mainwindow.h

@@ -93,6 +93,9 @@ private:
   template <typename T>
   T* AppendPanelInternal(QList<T*>& list);
 
+  template<typename T>
+  void SetUniquePanelID(T* panel, const QList<T*>& list);
+
   void RemoveTimelinePanel(TimelinePanel *panel);
 
   void RemoveProjectPanel(ProjectPanel* panel);