I'm using Win 10 Pro Build 106299 and it is fixed, at least on my machine. In Win 7 the switch was in Ease of Access Center, in Win 10 I can't find any links to the correct menu in the control panel.
Anyway, the fix (for me): open WINDOWS SETTINGS, search for MOUSE. There are about 6 mouse settings menus available, select the one that's titled CHANGE YOUR MOUSE SETTINGS. About halfway down the screen there's a switch labelled SCROLL INACTIVE WINDOWS WHEN I HOVER OVER THEM. Default is ON, set it to OFF.