I am using the LightningJS framework from Metrological for an app. In the docs it states:

Lightning has many other tricks up his sleeve to save performance, such as not having to render invisible parts (alpha:0 or visible:false) and detecting when branches are guaranteed to be out of screen.

However, when an element is not shown, the attribute visible is set to true, contrary to what I believed would happen.

Am I misunderstanding the documentation, or am I missing something? If so, how can I detect when an element is off-screen so I can turn its visibility off?