What patent has multi-touch applied for?

It should be a combination of software and hardware. If Microsoft and Google use similar multi-touch technology, but the software and hardware are different, you don't need to pay the patent fee. If the hardware and software are similar or the same, you have to pay the patent fee.

Functional similarity is not the basis for judging whether to pay patent fees. Using different technologies for exactly the same function is not patent infringement. The key depends on whether it is consistent with the patent claim. The claim has no writing function, only technical features.