Mousewheel on control always adds three!

Question

How come when you mousewheel over a trackbar three is always added?  I can't figure out where the event is coming from to stop it!  In my own mousewheel event I add ten to the value, but the total change is always 13.  Argh!!!  The value added it tied to your control panel -> Mouse -> Wheel Tab -> Lines to Scroll setting.

I need to either retrieve this setting and account for it or I need to find which event adds this value and stop it.  I have spent a lot of time on this and would appreciate any help.