SDL_UpdateRect and clipping

Hullo there,
I know that blits are automagically clipped to the edges of the
destination surface, but this doesn’t seem to be the reason when you
update.
Is that correct, and if so: is there a reason why it isn’t clipped?

Btw: Thank you so very much for SDL! It’s really a thrill to use - I
never imagined porting things to linux would be this painless…

Yrs. sincerely,
/morten bek