thank you at first for you help!
I also thought of using the PerformValidation method in the TextChanged event but wasnt sure good you confirmed it :)
What I do not like about the validation block that it is not compatible with the MVP Design Pattern which I am used to. The model is instantiated in the View and the ErrorProvider and ValidationProvider is bound to my textbox controls. I would like to
have a loose coupling like in WPF with MVVM Pattern where the View does not know of the Model etc... Do you have any suggestion how to use the Validation Block with MVP Design Pattern?