The forward and back buttons on the mouse don't work with VMware Workstation 12 Pro. I've installed several guest systems, and the problem is the same with all.
Adding these lines to the VMX file doesn't work and isn't a solution for ALL guests.
usb.generic.allowHID = "TRUE"
mouse.vusb.enable = "TRUE"
mouse.vusb.useBasicMouse = "FALSE"
I'd rather not spend another week and dozens of hours fixing this problem like I did the previous issue with VMware Workstation 12 Pro and mouse problems.
The forward and back buttons worked with VMware Workstation 11, 10, 9, 8, 7, and 6.