Thanks everybody for the comments. It looks like the 'Enter' event for each of the tab pages occurs before the controls on that page are updated from the DataSource. And it looks like the 'SelectedIndexChanged' from the tab control occurs after the updating. So, I can set a flag while any of the pages are being updated and ignore any of the 'changed' events from any of the controls during that time. Not too pretty, but it seems to do the job.