Stuart,
I have a simple suggestion for you! You might want to create and extra field on your point layer called "Edited", for example. It can be a short integer field to hole "1" or "0" to tell the point is edited or not. Then re-classify the symbology base on that field.
0 = non edited
1 = edited
Then, with your "onok" event, calculate "Edited" = 1
Hope this helps