Thanks for your confirmation.
I tested in Notepad on other three Windows10 laptops. And found different behavior on different laptop.
The version of AHK is 1.1.34.02.
The whole script is as follows:
!j::Send {Down}
!k::Send {Up}
!h::Send {Left}
!l::Send {Right}
The test scenario is:
Firstly, I input 100 lines with repeated content: 'aaaaaaaaaaaaaa' in Notepad.
Then I use alt+j/k/h/l to navigate, I will see letter j/k/h/l between letter a.
The point is the probability of occurrence is different, e.g. the one laptop is about 60%,
the other is about 5% more or less.
What is the cause of probability changing?
Is there any other stable solution for it? I means making probability zero.
By the way, I refered this links, but failed:
https://www.autohotkey.com/board/topic/61732-repeating-key-combo-problem/
Thanks!