The Back Button Dilemma

To add to what you're saying: bad developers are often under the impression that their app is the universe within which user activity happens. This is somewhat understandable, since their app is all that developer think about. But it's important to remember that while adding a button go up might be the optimal thing to do within your app, it is unlikely to be the optimal thing to do overall.

Design for the user, not for your ego.

Sounds like a dilemma to me, for the user at least. It doesn’t really matter who is to blame, right?

I agree that back should bring you back.

Not sure about Gmail. First of all, it doesn't behave the way you describe on my Nexus One. It always goes to the home screen when I switch to it, regardless of how I do it.

Second, is this really the best behavior? Or is the behavior you describe the best behavior? If you get a new message notification, and you tap on it, don't you usually want to see the new message?

And lastly, do you propose that applications should always implement "up" explicitly, or only when necessary? Because most of the time, they would just be duplicating functionality that already exists, thanks to the back button. But if you only show it when necessary, you're creating a situation where casual users won't really understand when and why they should use which UI element.

This can be taken too far. Imagine clicking on a mailto: link in your browser and being taken to email - while you're there, you read a few emails and end up back at your inbox. You're done, and you're "at the top" of the app. You want to get back to your browser. How do you do that? I've seen an email app that, under these conditions, pressing back makes you go through every single email you already read. In other words, it traces you back through every single Inbox-->Email-->Inbox loop you ever did. Not to mention what happens in the same app when you muck around the settings screen. Be prepared to go visit the settings screen again!

The problem here was that there are two ways to go "back" when reading an email. Press the back button, or clicking an on-screen UI element that took me back to the Inbox. One of them pops an item off the undo stack, and the other pushes one onto it. It's consistent, but frustratingly so.

I realize that I want to have my cake and eat it too, but at some point having an undo stack that is 30+ items deep doesn't really help me all that much.

I suppose it just goes to show that the meaning of Android's back button is way too overloaded (I think WP7 suffers from this across their other buttons as well).

I'm not too familiar with iOS, but may it be that iOS is emphasizing a "silo" view of apps (where you consistently stay within one app until you "escape" to the root), which Android deemphasizes the app in particular, in favor of a more unified feel?

It's not that the behavior is unclear, it's that going back is not always what you want to happen.

Sometimes, you jump directly into an app, but then, you want to do other things inside that app; since the back button normally is used to move up inside an app, it's not always obvious how to do that (and it's sometimes not possible at all).

But no one wants that flow. If I wanted that flow, I'd buy an iPhone so that I have to completely stop what I'm doing and switch tasks (not that I dare say anything bad about iOS multitasking).

I don't want to get a text, reply to it and then have to relaunch my previous app. A tap of the back button and I'm back to doing whatever I was before I sent the text.