Lol, the internal alphabet cursor position is actually stored as the
on-screen top-left position of the selected character, which this
function then maps back to a character index. At least that gets rid of
quite a bunch of PI false positives now.
Part of P0092, funded by Yanga.
I did consider not doing this, because "well, can't anyone who's
*actually* interested just diff the TH01 and TH02 implementations to
figure out the differences themselves", but that duplication ended up
feeling too filthy after all.
And hey, it's a nice excuse to update TH02's version to current naming
standards! 😛
Part of P0068, funded by Yanga.
nmlgc