title: Not showing notifications when receiving a push event when the PWA is opened
body: <p>This is a best practice question regarding the handling of push notifications in Pogressive Web Apps.</p>
  
  <p>I'm currently developing a web app which contains a chat functionality. I added push notifications so the user gets a notification (via the NotificationsAPI) every time he receives a new chat message. This works fine. But receiving tons of push notifications even though the user has the chat window open is not a good user experience. Therefore i'd like to not show a notification at all if the user has the app open.</p>
  
  <p>I know that not notifying the user about an incoming push is a critical topic and e.g. Chrome wants me to specify the <code>userVisibleOnly</code> flag. Is this a valid exception for not showing a notification or do you think i really need to show a notification every time a push is incoming? And if so, how can i deal with my problem? Anyone has any ideas how other apps are solving this issue?</p>