_zimfw_list_unuseds() {
  local -i i=1
  local zinstalled=(${ZIM_HOME}/modules/*(N/))
  local -r zdirs=(${(v)_zdirs})
  # Search into subdirectories
  while (( i <= ${#zinstalled} )); do
    if (( ${zdirs[(I)${zinstalled[i]}/*]} )); then
      zinstalled+=(${zinstalled[i]}/*(N/))
      zinstalled[i]=()
    else
      (( i++ ))
    fi
  done
  # Unused = all installed dirs not in zdirs
  _zunused_dirs=(${zinstalled:|zdirs})
  local zunused
  for zunused (${_zunused_dirs}) _zimfw_print -PR "%B${zunused:t}:%b ${zunused}${1}"
}