David,

I repspectfully disagree with my colleagues. If the defined behavior of the control is to change the form's property then that is what you should do. To do otherwise, for whatever reason, introduces an interdependency between the controls and the form.

Future revisions of the form may cause you to change or remove the control that is bound to the property. This would cause code in a seemingly unrelated control to then fail. If the second control updates the form property and then refreshes the form, there is no interdependency between the controls and future modifications won't have the same impact.