One of Windows longstanding frustrations was that if you hovered your mouse cursor over a window and tried to use the scroll wheel, nothing happened if the program wasn't currently active, even if you could see it. This was especially annoying when using a small-windowed program like Calculator or Notepad alongside a larger document, or on multi-monitor setups.
Microsoft's new operating system now supports the ability to scroll through inactive windows when you hover over them, and it's even enabled by default. Go to 'Settings->Devices->Mouse and Touchpad' to find it.
