Fix notification window close event bug

[Daytron]

Initial logic was the used of BlurListener on Window. But when user click on inner Window components it triggers the close event.

Also when clicking the notification button when the window is already popup, it just recreates a new popup window instead of closing it.

[Daytron]

Instead of using blur listener, listen for root layout click and from there close all opened windows.
Fixed with this commit c3fbc8a