Suggestion: allow mapping left and right CTRL, Alt, Shift keys separately

Currently, both left and right CTRL, Alt, and Shift keys map as the same key, ie if you press the left Shift key to map to a button, it shows as "Shift," and anywhere you had mapped by pressing the right Shift key becomes unmapped.

It could be useful to allow these left and right keys to be mapped separately. For instance, in a pinball game such as Last Gladiators, if I'm playing on keyboard I like to have the left flipper on left Shift and the right flipper on right Shift.

(Current behavior:

1. Go to Settings - Input - Configure
2. Click a blank spot in the mapping grid and press left CTRL, Alt, or Shift; these map as "CTRL," "Alt," or "Shift" rather than as "Left CTRL," "Left Alt," or "Left Shift"
3. Click a blank spot on the mapping grid and press the corresponding right-hand key of the left-hand CTRL, Alt, or Shift key you pressed previously == These also map as "CTRL," "Alt," or "Shift," and the left-hand version of that key you'd mapped previously becomes unmapped)