I will never understand why Xerox did not sue the pants off Jobs when he stole 99% of this visual gui design and then claimed forever onward that Apple was resp

I will never understand why Xerox did not sue the pants off Jobs when he stole 99% of this visual gui design and then claimed forever onward that Apple was responsible for it. The thing that killed this was at that time no company was going to spend close to the salary of a typist to outfit said typist with this kit. (I believe it was in the 10-20K range.)