Can't say for sure on FMPA 10 but FMPA 9 and FMPA 12 require a 2 finger drag up or down to scroll the drop down menus on OS X 10.8. Verify your system preference settings for the magic mouse.
I was talking with someone with FMPA 12 and she was able to do it with one figure slide. But maybe it just doesn't work in FMPA 10. I'll drag the scrollbar for now.