Send an official letter to Microsoft, and ask them bluntly
a) if they intend to sue you in the future,
b) what they suggest YOU should do for avoiding legal confrontation
this is a serious suggestion, i am not joking.
They will have to answer eventually, and their answer will give you an advantage in the future.
Either unacceptable patent wise/legally, or affirmative that they will take no legal action with/or without any suggestions for you or not.
