Eu não tenho 100% de certeza do que você procura, e algo assim? ...
#SingleInstance, Force
#NoEnv
#NoTrayIcon
#Persistent
; tilde allows LButton to click as normal vs. this routine capturing the click
; i.e., LButton will always click once prior to RButton click getting sent 1 sec later
~LButton::
StartTick:=A_TickCount
While GetKeyState("LButton", "P") && ((A_TickCount-StartTick)<1000) ; 1000ms hold-down requirement
Sleep 10
If GetKeyState("LButton", "P") ; If LButton is still down after loop exits, send RButton
SendInput, {RButton}
Return