Everything is patented. Microsoft has patent on double clicking. Better question is, is the patent enforceable? But even this is still the wrong question - given enough money and good enough lawyers, even a totally ridiculous case can be made to destroy you if they so wish.
So the only relevant question is, is there a financial interest to sue you? Are you a threat to a large corporation and their market share? If yes, no matter what you actually do or don't do, you can always get sued, or otherwise extorted, using legal, illegal or grey means.