I'm sure it wasn't the whole concept of a GUI that was being sued for, but that MS's rendition looked too much like Apple's. IIRC one of the consequences of that case was that Windows wasn't allowed to use proportional scroll bars - though at around that time the Amiga had proportional scroll bars, all the *nix windows managers have them but Apple haven't sued anyone else, yet.

When MS copy (and they do that all the time, or steal) they really do copy, like WP7's first iteration will have no copy+paste - just like the iphone