Thanks cgeier, but that did not help. I think that binding is not really designed for that. I don't think there is a way to have the BindingSource refresh the controls in winforms. I've thought of ds.applychanges, but that "commits" the changes somehow and it assumes that your "validation session" has ended.
No big deal of course, something like that is rather excetional and can be handled at form level.
Thanks anyway for caring.