qtui: Account for Qt 6 sending close events at shutdown

Author: jlindgren90

src/qtui/main_window.cc

@@ -223,15 +223,27 @@ MainWindow::MainWindow()
 }
 
 MainWindow::~MainWindow()
+{
+    // should have already been called in teardown(), but we'll
+    // make sure so that audqt isn't left with a dangling pointer
+    audqt::unregister_dock_host();
+
+    if (m_search_tool)
+        aud_plugin_remove_watch(m_search_tool, plugin_watcher, this);
+}
+
+// should be called before QApplication::quit() in
+// order to tear down the UI in an orderly fashion
+void MainWindow::teardown()
 {
     QSettings settings(m_config_name, "QtUi");
     settings.setValue("geometry", saveGeometry());
     settings.setValue("windowState", saveState());
 
+    // destroy plugin windows explicitly, otherwise Qt may send close
+    // events to them during QApplication shutdown, causing plugins to
+    // be disabled at next startup
     audqt::unregister_dock_host();
-
-    if (m_search_tool)
-        aud_plugin_remove_watch(m_search_tool, plugin_watcher, this);
 }
 
 void MainWindow::closeEvent(QCloseEvent * e)

src/qtui/main_window.h

@@ -41,6 +41,8 @@ class MainWindow : public QMainWindow, audqt::DockHost
     MainWindow();
     ~MainWindow();
 
+    void teardown();
+
 private:
     QString m_config_name;
     DialogWindows m_dialogs;

src/qtui/qtui.cc

@@ -69,7 +69,11 @@ class QtUI : public audqt::QtIfacePlugin
         }
     }
 
-    void quit() { audqt::quit(); }
+    void quit()
+    {
+        window->teardown();
+        audqt::quit();
+    }
 };
 
 EXPORT QtUI aud_plugin_instance;