IsBetween filter operator

Can you add filters for string ?
Do not start with
Do not end with
Is null or white space
Is not null or white space

Your RadDataFilter is great.  However, your documentation is lacking.  The control is not included in the SDK download and, the examples reference classes that aren't included in the documentation.  Look at the 
"Default Filter Editors" example.  In the example, you reference a behavior in the Example that has no supporting class and no way for me to see it.  Specifically, "Example.xaml":  behavior:MyFilterDescriptorBindingBehavior.FilterDescriptors="{Binding FilterDescriptors, Source={StaticResource model}}"

Hi,
a nice feature would be to hide each filteroperator separately. For example from the itempropertydefinition.

Regards