{P : Sort u} →
  {wi : Lean.Widget.WidgetInstance} →
    {alt : Lean.Widget.TaggedText Lean.Widget.MsgEmbed} →
      {wi' : Lean.Widget.WidgetInstance} →
        {alt' : Lean.Widget.TaggedText Lean.Widget.MsgEmbed} →
          Lean.Widget.MsgEmbed.widget wi alt = Lean.Widget.MsgEmbed.widget wi' alt' → (wi = wi' → alt = alt' → P) → P