I want to disable my Menu key (i.e. the key that calls up the same context menu as right clicking) so that I can use it when I'm playing Minecraft (I'm left handed so I use the mouse in my left hand and control movement with the cursor keys - the Menu key is in the perfect spot to be mapped to Sneak).

I have successfully remapped most keys in Minecraft (Options -> Controls) but when I try to map the Sneak function to Menu, Minecraft recognises that a key has been pressed but does not change it to Menu but leaves it as LSHIFT, which is no use to me.

I don't know why this happens but I suspect it's because Ubuntu is using the key for the context menu so I'd like to unmap it in the OS so it's available to use in Minecraft.

The Menu key is not listed anywhere in keyboard shortcuts. How do I disable it?