∀ {M : Type u_1} {X : Type u_2} [inst : TopologicalSpace M] [inst_1 : TopologicalSpace X] [inst_2 : Group M]
  [IsTopologicalGroup M] [inst_4 : MulAction M X] [DiscreteTopology X],
  ContinuousSMul M X ↔ ∀ (x : X), IsOpen ↑(MulAction.stabilizer M x)