So microsoft would be within their rights to take a 30% cut of all cash flows from subscriptions made using internet explorer? What about 30% of all sales of W

So microsoft would be within their rights to take a 30% cut of all cash flows from subscriptions made using internet explorer? What about 30% of all sales of Windows Software? Where does the ownership of the OS author end and the ownership of the 3rd party developer begin? What if Apple insisted upon 50%?