emulate -L zsh
setopt extendedglob

local opt keys
integer stat

while getopts "k:" opt; do
  case $opt in
    # Read the given number of keys.  This is a bit
    # ropey for more than a single key.
    (k)
    keys=$OPTARG
    ;;

    (*)
    return 1
    ;;
  esac
done
(( OPTIND > 1 )) && shift $(( OPTIND - 1 ))

local savelbuffer=$LBUFFER saverbuffer=$RBUFFER
local savepredisplay=$PREDISPLAY savepostdisplay=$POSTDISPLAY

LBUFFER="$2"
RBUFFER="$3"
PREDISPLAY="$PREDISPLAY$savelbuffer$saverbuffer$POSTDISPLAY
${1:-? }"
POSTDISPLAY=

if [[ -n $keys ]]; then
  zle -R
  read -k $keys
  stat=$?
else
  zle recursive-edit -K main
  stat=$?
  (( stat )) || REPLY=$BUFFER
fi

LBUFFER=$savelbuffer
RBUFFER=$saverbuffer
PREDISPLAY=$savepredisplay
POSTDISPLAY=$savepostdisplay

return $stat