Here is the response back from IG about this:

"The reason you can't find any documentation as to the order of client-side events for WebGrid is because there is no documentation currently available on the topic, not even available to us internally.  I do not know for certain why this is the case, though I suspect it's because of the sheer number of events WebGrid exposes and the many circumstances that may cause these events to occur in a different order.

I've forwarded your message to our Documentation team, as a request for such documentation to be added to NetAdvantage for .NET in a future release."