Enable umlaut replacement, with the option to revoke the replacement using backspace

umlaute.ahk

; #Warn  ; Enable warnings to assist with detecting common errors.
SendMode Input  ; Recommended for new scripts due to its superior speed and reliability.
SetWorkingDir %A_ScriptDir%  ; Ensures a consistent starting directory.

hscancel=backspace
hstime=1000
hsfrom = 
hsto = 

; UMLAUTE

:*?C:ae::
  replace("ae","ä")
return

:*?C:Ae::
  replace("Ae","Ä")
return

:*?C:oe::
  replace("oe","ö")
return

:*?C:Oe::
  replace("Oe","Ö")
return

:*?C:ue::
  replace("ue","ü")
return

:*?C:Ue::
  replace("Ue","Ü")
return

:*?C:Ss::
  replace("Ss","ß")
return

; REPLACE

replace(from,to)
{
  global hsfrom, hsto, hscancel, hstime
  hsfrom = %from%
  hsto = %to%
  send %hsto%
  hotkey, $%hscancel%, hscancel
  hotkey, $%hscancel%, on
  settimer, hsdisablecancel, -%hstime%
}

hscancel:
  hslen := strlen(hsto)
  send {bs %hslen%}%hsfrom%
; fall through
hsdisablecancel:
  hotkey, %hscancel%, off
return