IIRC in Kilofox there was some more detail about it, but I'd question the intuitivity of such a naked approach.
Probably a pgf with cbo and a plus button on page1 and an Editbox for textentry on page2 without page tabs is better

>I wonder if there is a way to use a combobox that also allows free text entry? The list has different values from an array, but if I enter a text that is not found in the list it blanks out on Lostfocus.