public void set_destroy_count_func (owned TreeDestroyCountFunc? func)
Warning: set_destroy_count_func is deprecated since 3.4.
This function should almost never be used.
Accessibility does not need the function anymore.
It is meant for private use by ATK for determining the number of visible children that are removed when the user collapses a row, or a row is deleted.
Function to be called when a view row is destroyed, or null
User data to be passed to
Destroy notifier for