(gobject:define-genum "GtkPropagationLimit" propagation-limit
  (:export t
   :type-initializer "gtk_propagation_limit_get_type")
  (:none 0)
  (:same-native 1))  

:none

Events are handled regardless of what their target is.

:same-native

Events are only handled if their target is in the same gtk:native widget as the event controllers widget. Note that some event types have two targets (origin and destination).