Notify when a zsh command ends in a shell not currently focused

.zshrc

# Requires zsh
# Requires xdotool

the_command="?????"

preexec()
{
  if [ "x$TTY" != "x" ]; then
    the_command="$2"
  fi
}

precmd()
{
  local the_status=$?
  if [ "$the_command" != "?????" -a "x$TTY" != "x" ]; then
    # window title should still be the current command, or we switched window
    local window_title=$(xdotool getwindowfocus getwindowname)
    if [ "$the_command" != "$window_title" ]; then
      local face="face-smile"
      if [ "$code_command" != "0" ]; then
        face="face-sad"
      fi
      notify-send --expire-time=2000 --icon=$face "'$the_command' terminated (code $the_status)"
    fi
  fi
}