UML static diagram: type of attribute ?

[EmotionalHibernation]

Hi,

I'm trying to design a UML diagram ( UML Static Structure ) in Visio and I need to specify my own custom type for an attribute. How do I this ? When I go the Type combo box I see a list of predefined types and it forces me to select one of those, I can't type whatever I want.

Screenshot at:

http://i.imgur.com/SV1ce.jpg

Regards, MadSeb