The data tools kfilter component uses a DropDownList component to list the fields available for building a query. It looks like there is no way to apply the :filterable prop to the DropDownList that allows a user to type inside the list in order to filter down the list. This is especially useful if you have hundreds of fields in your dropdown. Instead a user must scroll through the entire list to find the field they are looking for.

We also use this component in our older web forms application and this functionality is available in the old component.  I would suggest allowing the :filterable prop to be applied to the kfilter component which would be passed down to the child DropDownList component.