Regarding your motivation, I certainly agree with Dima
The existing keyboard is indeed far too basic.
For me tab, escape, and control keys would be nice, for instance in order to try to really use the emacs like editor zile that Iņigo has ported on the device itself. Also caps lock ...
I remember a proposal for some changes by allovertheglobe in
https://www.mobileread.com/forums/sho...eyboard&page=3
post # 36,
but then I realize that you are aware of this as you had already answered at that time ...