use async in example

examples/demo.py

@@ -8,15 +8,17 @@
 
 * Can be closed with Escape or by pressing the window close button.
 * In both cases, it should print "Close detected" exactly once.
-* Hit space to spend 2 seconds doing direct draws.
+* Hit "f" to spend 2 seconds doing direct draws.
+* Hit "s" to async-sleep the scheduling loop for 2 seconds. Resizing
+  and closing the window still work.
 
 """
 
 import time
 
-from rendercanvas.pyside6 import RenderCanvas, loop
+from rendercanvas.glfw import RenderCanvas, loop
 from rendercanvas.utils.cube import setup_drawing_sync
-
+from rendercanvas.utils.asyncs import sleep
 
 canvas = RenderCanvas(
     size=(640, 480),
@@ -39,13 +41,19 @@ async def process_event(event):
     if event["event_type"] == "key_down":
         if event["key"] == "Escape":
             canvas.close()
-        elif event["key"] == " ":
+        elif event["key"] in " f":
+            # Force draw for 2 secs
+            print("force-drawing ...")
             etime = time.time() + 2
             i = 0
             while time.time() < etime:
                 i += 1
                 canvas.force_draw()
-            print(f"force-drawed {i} frames in 2s.")
+            print(f"Drew {i} frames in 2s.")
+        elif event["key"] == "s":
+            print("Async sleep ... zzzz")
+            await sleep(2)
+            print("waking up")
     elif event["event_type"] == "close":
         # Should see this exactly once, either when pressing escape, or
         # when pressing the window close button.