As reported on the xorg-mailing list:
There's something wrong with the keyboard repeat rate, but I'm
not sure I understand it yet. Tests done using xserver-1.4 as on git branch origin/server-1.4-branch (last commit is 007e2239cf655...). Some symptoms:
5a: one of my keyboards now has a very high repeat rate by
default. Besides, if I change it to, for example, xset r rate 250
1, and keep a key pressed, I get one initial keypress event and
then after 250ms I start getting two keypress events at every
5b: on another keyboard, I get what I call "keyboard repeat
(de)acceleration": if I set the repeat rate to 200/sec, for
example, I get this rate on the first initial events but
then the rate gets back to "normal" after a few milisecs. The
same with a rate of 1/sec or whatever value.
BTW, during my tests with a high repeat rate, sometimes events
are sent to a different window where the mouse is located. Maybe
the two problems are correlated. (Bug #13114)
Can you please try again with the patch I put forward for #13114. this should fix 5a, not sure about 5b though.
Both problems are gone after applying the patch from bug #13114. Thanks!
*** This bug has been marked as a duplicate of bug 13114 ***
on Feb 23, 2017 at 18:56:09.
(provided by the Example extension).