set-surrogate in mode:host-text<%>

• (send a-mode:host-text set-surrogate surrogate) -> void
     surrogate : (union #f surrogate-object)

  Sets the current surrogate object to surrogate. If a surrogate has been set before, this method calls that object's on-disable-surrogate method. If surrogate is not #f, calls its on-enable-surrogate method.