Re: Flash index problem.

For now, it  seems to me that there are a couple of things that the text to
speech and screen reader manufacturers could be encouraged to do:

1) Provide a line-highlighting mechanism as a standard option (in addition
to the usual word-highlighting mechanism). In fact you say some software
already does this, so maybe the others just need the matter to be pointed
out to them. It probably hasn't occurred to them before, any more than it
has to most of us here! :-)

W3C could also help by specifically recommending that in their materials
for user agents and text to speech manufacturers.

2) The ones that already have such an option could also run the
prefers-reduced-motion CSS media query, and default to the
line-highlighting method where they find the user has set that option in
their system settings.

That would help users who may not have discovered the option in their text
to speech reader. I am assuming that users who find flashing a problem also
find animations problematic, and so may have set that setting. Though I
often wonder how many of such users know of the system setting - it seems
to me likely that many technical people would know, but not the little old
lady down the street!