Flash-alert: click the prompt message,don't remove the message. the removeAlert don't work

Frontend Web Development: The Big Nerd Ranch Guide Chapter 25: Components
1

flash-alert: click the prompt message,don’t remove the message. the removeAlert don’t work.

2

by click the header of page to remove alert, can set the template/application.hbs:
<header {{on ‘click’ this.removeAlert}}>

but lose the real requirements.
3

or ease to add A div in application.hbs: <div {{on ‘click’ this.removeAlert}}>
{{#if isAlertShowing}}
<FlashAlert @message={{alertMessage}} @alertType={{alertType}} close={{action ‘removeAlert’}} /> {{/if}}

</div>