Forgive me for asking a sort-off-offtopic question, but what's the reason terminals - and therefore the programs which run within them - offer such limited scope for ctrl-key usage. A lot of characters are not available for remapping, such as ctrl-numeric-digit, or ctrl-shift-anything etc. What's the root cause of this? Is it telnet related? ssh? And, assuming there's a compromise somewhere, would it be possible for the problem to be lifted with a config option which says "I'm using this shell locally on my chromebook - please don't inflict this 40 year old restriction on me"?