That helped me to figure it out.

But I had to create a separate Colorizer. (see below)

Is there a way to use the same colorizer as goToSelected?

Thanks!

myGSFont            = "xft:Noto Sans CJK KR:bold:pixelsize=10"
myColorizer  :: Window -> Bool -> X (String, String)
myColorizer  = colorRangeFromClassName
                  (0x31,0x2e,0x39) -- lowest inactive bg
                  (0x31,0x2e,0x39) -- highest inactive bg
                  (0x78,0x3e,0x57) -- active bg
                  (0xc0,0xa7,0x9a) -- inactive fg
                  (0xff,0xff,0xff) -- active fg

gridColorizer :: a -> Bool -> X (String, String)
gridColorizer _ True = return ("#00aa00", "black")
gridColorizer _ False = return ("#333333", "#cccccc")

myGSConfig :: t -> GSConfig Window
myGSConfig colorizer = (buildDefaultGSConfig myColorizer)
    { gs_cellheight   = 30
    , gs_cellwidth    = 200
    , gs_cellpadding  = 6
    , gs_originFractX = 0.5
    , gs_originFractY = 0.5
    , gs_colorizer = myColorizer
    , gs_font         = myGSFont
    }

-- spawnSelected Redefine
spawnSelected' :: [(String, String)] -> X ()
spawnSelected' lst = gridselect conf lst >>= flip whenJust spawn
    where conf = def
                   { gs_cellheight   = 30
                   , gs_cellwidth    = 200
                   , gs_cellpadding  = 6
                   , gs_originFractX = 0.5
                   , gs_originFractY = 0.5
                  , gs_colorizer = gridColorizer
                   , gs_font         = myGSFont
                  }

 , ((mod4Mask, xK_g), goToSelected  $ myGSConfig myColorizer)
 , ((mod4Mask, xK_y), spawnSelected' myAppGrid) 
 , ((mod4Mask, xK_u), runSelectedAction (buildDefaultGSConfig gridColorizer) 
                                        [ ("Chromium", spawnHere "chromium")
                                        , ("Hexchat", spawnHere "hexchat")