Ah ha!!
So the mice really are waltzing only to grace notes. (Grace notes are independent of the time signature.)
Yep, I do need to go back to math class. Still, an explicit example would go a long way in knowing which chapter to study. Any baboon can type numbers into a computer and it impresses other baboons. Pressing a button on an electronic piano is great; playing it yourself means, you didn’t learn this from the parrot in the tree next to yours.
