[Haskell] how to write an interactive program ? gui library to use ?

Hi all, 1/ I'd like to know how can I implement an interactive program (an editor) in haskell where some "things" have to be updated. The "things" can be text in a word processor, or a pixel array in a 2d graphics editor, and so on. Have I to pass the state (the "things") explicitely in the arguments of the main loop (a recursive function) ? Sorry if it's stupid... 2/ Another one concerning gui library: what's the best choice ? I need it to work both on linux and windows. I also need it can handle an OpenGL context. thanks a lot, minh thu