>I put a wait window in the programmatic change event of the checkbox and it is not firing (as it does in a textbox) when the value changes due to the checkbox being bound to a logical field in a table. So there can be a reason to use an A/A in this control imho. Do you get this behaviour?

Nope, ProgrammaticChange is fired when you do o.Value = '' ect., so an Assign method in that case would work, but why add it when there already is this? What you're looking for is InteractiveChange(), it fires when the property is changed by the user. An Assign method won't trap this event either.