GUI SUGGESTIONS?

I'm looking to supply a GUI to aid users in the customization part of my project. The customization involves the users doing a lot of typing, so I'm gonna need text edit fields, text input boxes, and things like that. Can someone point me in the direction of where I can find some Ruby code that I can use for this?

Ideally, I wanted the GUI to be part of RPG Maker XP so that I can integrate it with the game itself, which is an RPG Maker XP game. But I've not been able to find working scripts for graphical user text input and editing, so I kind of suspect that there are none.

Plan B is to use plain old Ruby to create a separate executable. Anyone want to suggest where I can get the suitable libraries or gems or whatever it is I need to build a GUI with a minimum of fuss?