xmonad - name the submap keys

xmonad.hs

import qualified XMonad.Util.NamedActions as NamedActions
import qualified Data.Map as M

keybinds :: XConfig Layout -> [((KeyMask, KeySym), NamedActions.NamedAction)]
keybinds conf = let
  subKeys str ks = NamedActions.subtitle str : mkNamedKeymap conf ks
  in
   subKeys "Scratchpads"
   [
   ("M-S-o", NamedActions.addName "submap" $ submap . M.fromList $
            [
              ((0, xK_s),    namedScratchpadAction scratchPads "spotify-nsp")
            , ((0, xK_d),    namedScratchpadAction scratchPads "discord-nsp")
            , ((0, xK_t),    namedScratchpadAction scratchPads "tmux-nsp")
            ])
   ]

Replace the plain submap. M.fromList bit with the special XMonad.Util.NamedActions.submapName (it already takes a list) to get it to propagate the action descriptions "upwards".

https://hackage.haskell.org/package/xmonad-contrib-0.16/docs/XMonad-Util-NamedActions.html#v:submapName