(:idle ()
	       (sdl:with-timestep ()
				  (do-update))
	       ;; this lets slime keep working while the main loop is running
	       ;; in sbcl using the :fd-handler swank:*communication-style*
	       #+(and sbcl (not sb-thread)) (restartably
					     (sb-sys:serve-all-events 0))
	       (restartably
		(draw)
		(gl:flush)
		(sdl:update-display))))))