SelectItem setPickListFields question or feature request

I am using a SelectItem with a drop down list (setPickListFields(...) ). It works well.

However I would like to be able to :

- either display the grid filter header in order to type in filtering strings
- either type in characters in the SelectItem, to filter down items, like the standard behavior of the SelectItem widget, but in this case with a filtering on the display field.

Is there any hint to do such a thing ?

Thank you,
Elie