PROTO slide-background [
  exposedField SFInt32 whichChoice -1
  ]{
  DEF DECORATION Switch {
  whichChoice IS whichChoice
  choice [
  @include proto-slide-backgrounds-spheres.vr
  @include proto-slide-backgrounds-red.vr
  @include proto-slide-backgrounds-snow.vr
  @include proto-slide-backgrounds-plane.vr
  ]
  } 
  }