Sadly, not even Google's apps do this correctly all of the time. Google Voice is a particularly dreadful offender. If you click on a Google Voice notification,

Sadly, not even Google's apps do this correctly all of the time. Google Voice is a particularly dreadful offender. If you click on a Google Voice notification, "back" doesn't take you "back" and it doesn't take you "up". AFAICT, it takes you "back within the app", which is often crazy. Here's the scenario I just tried: 1. I was in Google Voice talking to person A. 2. I left Google Voice and was in another app X. 3. A text arrives from person B and I get a notification from Google Voice. 4. I click on the notification and go to my conversation with person B in Google Voice. 5. I hit "back". It didn't go back to app X (the Right Thing). It didn't go to my conversation list in Google Voice (the more common wrong thing). Instead, Google Voice, of course, goes to my conversation with person A! I can only hope that one of the reasons the Android team published their design guidelines was to publicly shame the developers of substandard Google apps for Android.