add_button_with_target_value

Description:

public void add_button_with_target_value (string label, string action, Variant? target)

Adds a button to this that activates action when clicked.

action must be an application-wide action (it must start with "app.").

If target is non-null, action will be activated with target as its parameter.

this	a Notification
label	label of the button
action	an action name
target	a Variant to use as `action`'s parameter, or null