Well, not sure about the styles, if you want to map to native widgets ...
I still remember Cyphre's remark in Brno - how many usefull widgets are there in the OS anyway? How cross platform are they? So we have fields, areas, buttons, images, radio buttons, check boxes. What about more complex ones, as grids? Win32 API apps look uglier, than old 70ish unix clone. And - design sells. Let's hope, that this time, we are going to dress that :-)