[pygame] updating rects

[enrike <enrike@altern.org>]

hi

I hav two big rects that i need to update. But the are overlapping one
each other.
I would like to update rect1 and then the non-overlaping part of rect2.
How could i do this using the rect intersecting functions of pygame?  or
is it the update function clever enough to deal with this on its own? (i
suspect it is)

yet another question.
I am drawing the external lines of a rectangle (i am using draw.rect but 
i could also use draw.lines i guess). Instead of updating the whole 
surface of the rect I thought it would be cheaper to update the lines 
themselves. But it looks to me that its actually updating the whole 
rectangle even if i pass to the update funtion the rects for the lines. 
Am i doing something wrong?

thanks

--
enrike