wayland: Guard surface_frame_listener for OpenGL, document why it exists
diff --git a/src/video/wayland/SDL_waylandwindow.c b/src/video/wayland/SDL_waylandwindow.c
index 50b16d1..2e4edcd 100644
--- a/src/video/wayland/SDL_waylandwindow.c
+++ b/src/video/wayland/SDL_waylandwindow.c
@@ -1012,8 +1012,14 @@ int Wayland_CreateWindow(_THIS, SDL_Window *window)
wl_compositor_create_surface(c->compositor);
wl_surface_add_listener(data->surface, &surface_listener, data);
- /* fire a callback when the compositor wants a new frame rendered. */
- wl_callback_add_listener(wl_surface_frame(data->surface), &surface_frame_listener, data);
+ /* Fire a callback when the compositor wants a new frame rendered.
+ * Right now this only matters for OpenGL; we use this callback to add a
+ * wait timeout that avoids getting deadlocked by the compositor when the
+ * window isn't visible.
+ */
+ if (window->flags & SDL_WINDOW_OPENGL) {
+ wl_callback_add_listener(wl_surface_frame(data->surface), &surface_frame_listener, data);
+ }
#ifdef SDL_VIDEO_DRIVER_WAYLAND_QT_TOUCH
if (c->surface_extension) {