diff --git a/Overview.md b/Overview.md
index 95c9f38..beefa99 100644
--- a/Overview.md
+++ b/Overview.md
@@ -5,9 +5,9 @@ Singe uses an event-driven programming model.  What this means is that Singe con
 The most basic Singe script that provides all the existing "callbacks" used by Singe looks like this:
 
 ```lua
--- Singe Game Skeleton
+-- Singe Game Skeleton.
 
--- Load the Singe Framework
+-- Load the Singe Framework.
 dofile("Singe/Framework.singe")
 
 -- Declare any global variables you need here.
@@ -31,6 +31,7 @@ function onMouseMoved(x, y, xr, yr, which)
 end
 
 function onOverlayUpdate()
+   return(OVERLAY_UPDATED)  -- Or OVERLAY_NOT_UPDATED if no drawing was done.
 end
 
 function onShutdown()