I've just encountered a problem when someone using Safari tried to add a link. They clicked on add.cgi?ID=1 (for example) and were redirected to login (through Community) and once logged in it took them to the add.cgi page but the ID=1 was encoded strangely and they got an error message as though there was no ID. I'm not sure whether the login redirect doesn't work with Safari generally or whether they really did something strange.

I tried exactly the same thing in Explorer and the url was resolved normally.