Add small comment

objects/oIntroController.object.gmx

@@ -27,6 +27,7 @@
             <kind>1</kind>
             <string>alarm[0] = 180;
 txt = get_text("Title", "ControllerRecommended");
+// If on Linux, quickly toggle fullscreen to get rid of GM:S mess. Seemed to be the best place to do that.
 if (os_type == os_linux && global.opfullscreen) {
     window_set_fullscreen(false);
     window_set_fullscreen(true);