window: undo last commit (was a trainwreck). explicitly close child windows to avoid GL issues. fix bug with window parenting in second multiplayer instances.

src/frontend/qt_sdl/EmuInstance.cpp

@@ -204,7 +204,7 @@ void EmuInstance::createWindow(int id)
     if (windowList[id])
         return;
 
-    MainWindow* win = new MainWindow(id, this, topWindow);
+    MainWindow* win = new MainWindow(id, this, mainWindow ? mainWindow : topWindow);
     if (!topWindow) topWindow = win;
     if (!mainWindow) mainWindow = win;
     windowList[id] = win;

src/frontend/qt_sdl/Window.cpp

@@ -809,18 +809,6 @@ MainWindow::MainWindow(int id, EmuInstance* inst, QWidget* parent) :
 
 MainWindow::~MainWindow()
 {
-    if (windowID == 0)
-        emuInstance->saveEnabledWindows();
-    else
-        saveEnabled(false);
-
-    QByteArray geom = saveGeometry();
-    QByteArray enc = geom.toBase64(QByteArray::Base64Encoding);
-    windowCfg.SetString("Geometry", enc.toStdString());
-    Config::Save();
-
-    emuInstance->deleteWindow(windowID, false);
-
     if (hasMenu)
     {
         delete[] actScreenAspectTop;
@@ -841,6 +829,36 @@ void MainWindow::saveEnabled(bool enabled)
     enabledSaved = true;
 }
 
+void MainWindow::closeEvent(QCloseEvent* event)
+{
+    if (emuInstance)
+    {
+        if (windowID == 0)
+            emuInstance->saveEnabledWindows();
+        else
+            saveEnabled(false);
+    }
+
+    // explicitly close children windows, so the OpenGL contexts get closed properly
+    auto childwins = findChildren<MainWindow *>(nullptr, Qt::FindDirectChildrenOnly);
+    for (auto child : childwins)
+        child->close();
+
+    if (!emuInstance) return;
+
+    QByteArray geom = saveGeometry();
+    QByteArray enc = geom.toBase64(QByteArray::Base64Encoding);
+    windowCfg.SetString("Geometry", enc.toStdString());
+    Config::Save();
+
+    emuInstance->deleteWindow(windowID, false);
+
+    // emuInstance may be deleted
+    // prevent use after free from us
+    emuInstance = nullptr;
+    QMainWindow::closeEvent(event);
+}
+
 void MainWindow::createScreenPanel()
 {
     if (panel) delete panel;

src/frontend/qt_sdl/Window.h

@@ -242,6 +242,8 @@ private slots:
     void onScreenEmphasisToggled();
 
 private:
+    virtual void closeEvent(QCloseEvent* event) override;
+
     QStringList currentROM;
     QStringList currentGBAROM;
     QList<QString> recentFileList;