[Gambas-user] How can I distinguish between left shift key and right shift key?

[Bruce]

(This is very short answer based on a 300 page thesis I just wrote on 
"keyboards and why you can't see them anymore".)

Shift and Ctl are "modifiers". So is "Alt" and possibly "Fn" by the way.

Because of the many layers of software between your project and the 
actual keyboard that hide the physical layer way back in the O/S, or + + 
  especially "X" it has been determined that "thou need not know" which 
actual modifier key was used.

You could try getting as close to the O/S as possible using some library 
or other but it is still hard given "keymaps" and the like.

man showkey
and then the rest

best wishes
b