Keybindings conflict in Linux Mint 17


I’m having a problem with the Ring Select function (Alt-RMB short cut). In Linux Mint this is linked to a window menu, and can not be used in Blender.

Following advice from other threads I changed this in ccsm to <Super>Button3 to free the keybinding for use in Blender, but this change doesn’t have any effect.

Any ideas?
Or any alternative ways to get this ring select function to work?