<p>Just wondering what people think is the best practice when implementing an IValueConverter which does not have a meaningfull ConvertBack implementation (or one that is only to be used as OneWay)?</p>

<p>Should it throw (and in that case what exception), return null or return some default value. </p>

<p>Thoughts?</p>

The documentation for
```
IValueConverter.ConvertBack
```
recommends returning
```
DependencyProperty.UnsetValue
```
.
The data binding engine does not catch
  exceptions that are thrown by a
  user-supplied converter. Any exception
  that is thrown by the ConvertBack
  method, or any uncaught exceptions
  that are thrown by methods that the
  ConvertBack method calls, are treated
  as run-time errors. Handle anticipated
  problems by returning
  DependencyProperty.UnsetValue.