DataBinding is all powerful and good, but I just ran into an issue with the PasswordBox control...no data binding allowed on the Password property, since it's not a Dependency Property.

Now, I'm ok with all the password security issues, but no data binding means no ValidationRules.  If you are building a form for creating new account, the ValidationRules are SO easy to use and create you own validators.  Building a RegexValidationRule that takes in a pattern is ideal for just about everything.  However, you can't use in on the PasswordBox, which totally sucks.  With Regex you could write patterns to validate complex password requirements.  Instead, I only see the option of validating on submit button click, or wire up to a TextChanged event and test it as the user types.  ??

It would have been nice to allow data validation on the PasswordBox.Password property.