inverted monitor

src/qt/qt_mainwindow.cpp

@@ -850,3 +850,18 @@ void MainWindow::on_actionResizable_window_triggered(bool checked) {
     emit resizeContents(scrnsz_x, scrnsz_y);
 }
 
+static void
+video_toggle_option(QAction* action, int *val)
+{
+    startblit();
+    *val ^= 1;
+    action->setChecked(*val > 0 ? true : false);
+    endblit();
+    config_save();
+    device_force_redraw();
+}
+
+void MainWindow::on_actionInverted_VGA_monitor_triggered() {
+    video_toggle_option(ui->actionInverted_VGA_monitor, &invert_display);
+    video_copy = (video_grayscale || invert_display) ? video_transform_copy : memcpy;
+}

src/qt/qt_mainwindow.hpp

@@ -57,6 +57,7 @@ private slots:
     void on_actionHardware_Renderer_OpenGL_triggered();
     void on_actionSoftware_Renderer_triggered();
     void on_actionResizable_window_triggered(bool checked);
+    void on_actionInverted_VGA_monitor_triggered();
 
     void refreshMediaMenu();
     void showMessage_(const QString& header, const QString& message);