DolphinQt: Allow changing "Render to Main Window" during emulation.

Source/Core/DolphinQt/Config/Graphics/GeneralWidget.cpp

@@ -206,7 +206,6 @@ void GeneralWidget::BackendWarning()
 void GeneralWidget::OnEmulationStateChanged(bool running)
 {
   m_backend_combo->setEnabled(!running);
-  m_render_main_window->setEnabled(!running);
   m_enable_fullscreen->setEnabled(!running);
 
   const bool supports_adapters = !g_backend_info.Adapters.empty();

Source/Core/DolphinQt/MainWindow.cpp

@@ -1546,8 +1546,7 @@ void MainWindow::NetPlayInit()
   Discord::InitNetPlayFunctionality(*m_netplay_discord);
   m_netplay_discord->Start();
 #endif
-  connect(&Settings::Instance(), &Settings::ConfigChanged, this,
-          &MainWindow::UpdateScreenSaverInhibition);
+  connect(&Settings::Instance(), &Settings::ConfigChanged, this, &MainWindow::OnConfigChanged);
   connect(&Settings::Instance(), &Settings::EmulationStateChanged, this,
           &MainWindow::UpdateScreenSaverInhibition);
 }
@@ -1680,6 +1679,24 @@ void MainWindow::NetPlayQuit()
 #endif
 }
 
+void MainWindow::OnConfigChanged()
+{
+  UpdateScreenSaverInhibition();
+
+  if (m_render_widget->isVisible())
+  {
+    const bool is_rendering_to_main = m_render_window == nullptr;
+
+    const bool render_to_main_window = Config::Get(Config::MAIN_RENDER_TO_MAIN);
+
+    if (is_rendering_to_main != render_to_main_window)
+    {
+      HideRenderWidget();
+      ShowRenderWidget(render_to_main_window);
+    }
+  }
+}
+
 void MainWindow::UpdateScreenSaverInhibition()
 {
   const bool inhibit = Config::Get(Config::MAIN_DISABLE_SCREENSAVER) &&

Source/Core/DolphinQt/MainWindow.h

@@ -219,6 +219,7 @@ private:
 
   QStringList PromptFileNames();
 
+  void OnConfigChanged();
   void UpdateScreenSaverInhibition();
 
   void OnStopComplete();