Middle click does work on my Windows 8 start screen; it always launches a new instance.
It doesn't do anything on my Windows 7 machine's start menu, though. But that's no problem because left click does what I want.
Testing a bit more... Now I see! In Windows 7, middle click works on the taskbar but not in the Start menu. In Windows 8, it works on both.
Middle click does work on my Windows 8 start screen; it always launches a new instance.
It doesn't do anything on my Windows 7 machine's start menu, though. But that's no problem because left click does what I want.
Testing a bit more... Now I see! In Windows 7, middle click works on the taskbar but not in the Start menu. In Windows 8, it works on both.