Odd bug with 'solve'

[parisse]

Not sure I understand all you said, because my English is not good enough, so maybe my answer will not correspond to what you say (and it is of course my view, not that of Cyrille).
I believe it is essential to teach students things that will still be true/useful 30 years in the future. For math/CAS/calculators, that means being capable to input a commandline, independently of the UI. 2d input is good but it should not be used as an excuse not to teach how to enter a valid 1d expression with operator precedence and parenthesis (and this is certainly a good thing if you want later to write a program). Commandlines should be easily copied, exchanged and pasted from one software to another one, and that is in favor of using plain ascii text. Menu or keyboard help is nice, but I think it should enter a normal i for sqrt(-1), and not a fancy i. For comparison, I would certainly recommend teaching Unix commands in a terminal to CS students.
This is probably not a view shared by many math teachers. Perhaps it comes from the fact that I'm totally lost with UI that are not text-oriented, like those you find more and more these days (e.g. on smartphones), I simply can not associate a function for most pictures I see unlike with a classical textmenu entry (and obviously most users are built differently than I am).