I have a TextBox displaying the time part of a DateTime:

```
<TextBox HorizontalAlignment="Left" Height="23" Margin="0,13,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="120" Validation.Error="Validation_OnError">
    <TextBox.Text>
        <Binding Path="MyDate" StringFormat="HH:mm" NotifyOnValidationError="True" UpdateSourceTrigger="PropertyChanged">
            <Binding.ValidationRules>
                <c:TimeValidator></c:TimeValidator>
            </Binding.ValidationRules>
        </Binding>
    </TextBox.Text>
</TextBox>

```

Is it possible to do the validation on property change, and the conversion on lost focus?

I want to have the validation on property changed, but I want to have my data source updated on lost focus. Otherwise, the converter will kick in while the user is editing in the TextBox. This might be a problem if the values is `10:50` and the user deletes the last number, so that the value becomes `10:5`. The converter will then convert this to `10:50`. This is okay to do on lost focus, but not on property changed. But for the sake of the validator, i want to validate on property change so the user have the red border as long as the entered value is not valid.