I need a simple framework like MVC, but with an improved looking.
Another route might be to use a web browser with a HTML GUI on the desktop. Use Seaside to produce HTML and manage state, scriptaculous for some extra effects.
Hmm, other software (like Firefox) is accepted even with non-native look and feel.
Further down that road you can create an interface just like Mozilla / Firefox by using the Gecko layout engine where widgets are specified in XML (XUL)
http://developer.mozilla.org/en/docs/XULRunner
Callbacks could be done as local HTTP requests, again. Using Gecko would also give you vector graphics (SVG).
-- Matthias