add_action

Description:

public void add_action (string action, string label, owned ActionCallback callback)

Adds an action to a notification.

When the action is invoked, the specified callback function will be called, along with the value passed to user_data.

this	The notification.
action	The action ID.
label	The human-readable action label.
callback	The action's callback function.
free_func	An optional function to free `user_data` when the notification is destroyed.
user_data	Optional custom data to pass to `callback`.