The soul is dyed the color of its thoughts. Think only on those things that are in line with your principles and can bear the light of day. The content of your character is your choice. Day by day, what you do is who you become. Your integrity is your destiny - it is the light that guides your way. - Heraclitus
Exactly. Unfortunately, the UML is not complete and one of the things that it's missing is a standard way to model UI stuff. It's also missing a standard way to model a data schema, although that will hopefully change soon now that there is an OMG RFP for a UML data model. And it's missing a business process model and a standard way to model business rules (although they're working on that finally).
Know what also might be cool, although you cna use other things to do the same, but a formal Unit Test diagram, or Functional Test Diagram. I don't know, just throwing out fish.