From Xojo Documentation
The CheckBox has been clicked or the value has been changed programmatically. A right-click does not trigger the Action event.
If the the CheckBox value has been changed, either programmatically or by the user, then you may want to also cause another action to occur. In this event, you can take the action you need. This example could be used to update an App preference value based on the CheckBox setting:
This code makes a TextArea read-only based on a CheckBox setting: