[BRLTTY] brltty5.2 alpine2.11 cursor tracking

[Aura Kelloniemi]

Hello

Dave Mielke <dave at mielke.cc> writes:
 > Right now, the handler that processes a screen update alert is scheduled to 
 > execute immediately. My theory is that it might be better to schedule it to 
 > occur a few milliseconds later.

I tried the git head. My expert test bench looked like this:

Test #1: emacs
M-x display-time-mode (display time on mode line)
Configuration: display-time-format was set to "<%H.%M.%S>" and
  display-time-interval to 1 (in seconds)
Then I split the window in two (C-x 2)

Test #2: top
Just execute top

With pre-patched BRLTTY both emacs and top tests caused horrible flicker on
the braille display. After the update the flicker is reduced a bit in the
first case, but it does not make emacs with display-time-mode and two windows
usable with cursor tracking enabled. Top remains inaccessible.

I would prefer a solution which immediately updates the braille display, but
delays cursor tracking. BRLTTY could cache the cursor position when cursor
tracking is enabled, and if the cursor moves and does not return to the
original cached position within a few (say 20-100) ms, then follow the cursor.

I think that the problem with Dave's attempt to fix this problem was that
screen updates just take a longer time than what was suspected. However, for
top for example, the screen update takes a noticeably long time (perhaps
around 100 ms, but this is just a guess).

-- 
Aura