Couldn't match type `(W.Stack a1 -> Maybe (W.Stack a1)) -> W.StackSet i0 l0 a1 s0 sd0 -> W.StackSet i0 l0 a1 s0 sd0'with `W.StackSet
                             WorkspaceId (Layout Window) Window ScreenId ScreenDetail'
      Expected type: WindowSet
        Actual type: (W.Stack a1 -> Maybe (W.Stack a1))
                     -> W.StackSet i0 l0 a1 s0 sd0 -> W.StackSet i0 l0 a1 s0 sd0
    * Probable cause: `W.modify' is applied to too few arguments