After doing tests with Windows 95, 3,1, NT 4.0, and 2000 I can say this bug appears to be fixed.
** Changed in: qemu Status: Incomplete => Fix Released -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1785485 Title: Mouse moves erratically when using scroll wheel on Windows NT 4, Windows 95, and Windows 3.1 guests Status in QEMU: Fix Released Bug description: QEMU version: 3.0.0 RC3 Guests: Windows NT 4.0, Windows 95, Windows 3.1 Program: When the user uses the scroll wheel, the mouse's movement becomes erratic. This is noticed immediately when the scroll wheel is used. Sometimes the problem can be fixed by moving the scroll wheel some more. My theory is this problem is because of the lack of support for the Microsoft Intellimouse in these guest operating systems. To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1785485/+subscriptions