https://lexikos.github.io/v2/docs/Tutorial.htm#s22 (and the offline help) reads:
I assume it is supposed to be #HotIf WinActive(WinTitle).b. Window specific hotkeys/hotstrings
Sometime you might want a hotkey or hotstring to only work (or be disabled) in a certain window. To do this, you will need to use one of the fancy commands with a # in-front of them, namely #HotIf, combined with the built-in function WinActive or WinExist:
#HotIf WinActivate(WinTitle)
#HotIf WinExist(WinTitle)