You're comparing platforms and applications as if they were the same thing. OpenOffice is a single application. No one is going to have any trouble using that

You're comparing platforms and applications as if they were the same thing. OpenOffice is a single application. No one is going to have any trouble using that code base. The correct comparison is to Java. Oracle is currently suing Google over Sun's patents on Java. And people are fleeing Java in droves. And the language around Mono's licensing of patents is pretty transparently designed to give Microsoft the option of suing people building on Mono.