Trying to actually turn off the behaviour seems to be all but impossible, but I do know a way to modify it, although I have no idea how that will fit in with your Autodesk software shortcuts.
Anyway this is how to do it.
If you don't have dconf-editor then go into the package manager and install dconf-tools. When you have done that you can open dconf-editor from the main menu. In there you have to navigate to org.gnome.desktop.wm.preferences. In the right hand pane click the option 'resize with right button'. The resize option will now become Alt/right mouse button instead of Alt/middle mouse button.
Fujitsu Lifebook AH532. Intel i5 processor, 6Gb ram, Intel HD3000 graphics, Intel Audio/wifi. Realtek RTL8111/8168B Ethernet.Lubuntu 13.10,Ubuntu12.10 (Unity), Mint16 (Cinnamon), Manjaro (Xfce).