Oh i see what I did wrong...
I thought another user had to surf to
http://idisk.mac.com/membername/public
and then put some docs in.
If you do it that way, he always asks your .mac username and password.
But appearantly you have to do it via:
Go -> Idisk ->Other User's Idisk Public...
Sorry i'm new to the idisk.
I don't understand: if somebody wants to put something in your public folder, you have to give him your .mac accountname and password! But then he can peep in (and damage) your other folders (backup, pictures online...) too!
I think I'm seeing it wrong. Can...