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