testWM: visible background + auto-spawn one terminal on startup

examples/testwm.cpp

@@ -239,6 +239,11 @@ static void on_new_output(void* data) {
 	S->outputs.push_back(so);
 	S->layout.add_auto_output(o);
 	wl_event_source_timer_update(S->scheduler_source, 0);
+	static bool spawned = false;
+	if (!spawned) {
+		spawned = true;
+		spawn();
+	}
 }
 
 static void on_new_input(void* data) {
@@ -313,6 +318,10 @@ int main() {
 	S->cursor.on_axis(on_axis);
 	S->cursor.on_frame(on_frame);
 
+	float bg_color[4] = {0.08f, 0.08f, 0.12f, 1.0f};
+	wlr::Rect bg(wlr_scene_rect_create(S->scene.root(), 4096, 4096, bg_color));
+	(void)bg;
+
 	S->backend.on_new_output(on_new_output);
 	S->backend.on_new_input(on_new_input);
 	S->xdg_shell.on_new_toplevel(on_new_toplevel);