I'd actually just like to know the number of mouse buttons a laptop has (Apple: 1, Hackintosh: 2), but I'm guessing the answer to this would be interchangeable with the answer to the more general question above.
Edited to clarify about counting built-in mouse buttons: I'm aware you can use an external two-button mouse or control-click, but I'm specifically interested in the number of built-in hardware buttons: The app uses the laptop's onboard button(s) for paging up/down on a window that can change its rotation (which changes the scroll direction of the left/right buttons), and it's a better user experience if the app knows whether there are actually two side-by-side buttons or just a single control surface.