Bug 1060727 - [CMAS] Duplicated notifications in system tray when dismiss the attention screen by tapping on home button

- Close app while home button clicked (title display to none and visibility hidden)
It's interesting about the expected result and actual result: When we open the multiple attention window currently, closing the opener will only close the latest child window, and previous child windows will still exist(but opener is null). The behavior that system app what is app will only have one attention window, so previous one should be closed while app opens a new attention window. Alive thought it's a bug and we should solved it in the future.

But the expected behavior will not meet the UX requirement since they expects that previous screen should stay instead of closed by new one. So maybe we will need to cache the attention window and reopen when close the latest one. We can open a follow up for it but need to wait for attention screen bug fixed first, wdyt?