DataTrigger where value is NOT null?

Question

I know that I can make a setter that checks to see if a value is NULL and do something. Example:

Answer 1

Converter:

public class NullableToVisibilityConverter: IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return value == null ? Visibility.Collapsed : Visibility.Visible;
    }
}

Binding:

Visibility="{Binding PropertyToBind, Converter={StaticResource nullableToVisibilityConverter}}"