autohotkey - How do I break a while-loop with setTimer? - Stack Overflow

B needs to run 1000ms after the most recent press of A (if B is pressed 100ms after A then B must first sleep 900ms). It should also run normally if no instance of A is detected in the last 1000ms of pressing B. How do I achieve this using AutoHotkey v2?

a_var:=false

a::{
    global a_var
    if a_var=false{
        a_var:=true
        setTimer a_timer, -1000
    }
}

a_timer(){
    global a_var:=false
}

b::{
    global a_var
    while a_var{
        sleep 10 ;setTimer stops working, loop turns infinite
    }
    msgbox "success" ;needs to run 1000 ms after the most recent instance of a is pressed
}

setTimer stops running once it enters the while loop.