Cassie had been a smoker for 40 years. she did not disclose this information to her family until she got diagnosed with lung cancer. in this scenario, this information moves into the of her johari window.

Open Pane

Explanation: Open pane of the Johari window describe about the information and behavior that is known to the individual as well as people around him/her. The information and behavior are in the open phase to provide knowledge and communication with others.

According to the case mentioned in the question about Cassie states that the information of smoking was firstly only known by her and she did not share with other ,thus it was in secret pane .

But after detection of the lung cancer ,the news is known by her and others as well.Thus the information is known by her and family .In this case she enters the open pane in accordance with Johari window.