Modes (p.oxbow.0.1.1.doc.oxbow.ops.Oxbow

val handle : 
  Oxbow_state.Wm.t ->
  Oxbow_state.Seat.t ->
  Oxbow_ipc.Command.Keymap.Mode.t ->
  (Yojson.Safe.t option, string) result

handle wm seat cmd handles cmd.

Effects: mutates WM state