Aza recently posted about the problem with the home button on many modern touch devices. I empathize with the problem he mentions as I oftentimes find myself nervously hitting the home button when trying to get to the root of my current mental context (which is the application).
However, I can’t say I agree with his proposed solution (and it seems many of the commenters on his post have the same issue with it that I do). The camera model, for me at least, doesn’t really work because I actually find the autofocus button on modern camera’s to be mentally taxing. I seem to find myself hovering on the press of the button, hoping I don’t accidentally press too hard and spend more thought in the actual action of dealing with the machine rather than focused on the shot I’m using the machine to capture.
The other aspect I dislike about this model is that it requires a hardware change for something I think can be a software change.
There seem to be 2 issues that are mentioned in his post:
1. users accidentally pressing home to jump to the application home
2. an easier way navigate backwards and forward in our navigation timeline
Rather than overloading the Home button (which is already used for multiple purposes, such as going to the home screen of the phone, jumping to spotlight, force quitting apps, navigating between apps), we already have a place in the UI for handling this, which is the back button.
Pressing and holding down on the back button will open up a list view which will show your current location in the overall app navigation hierarchy. This could either be just strictly in the scope of your navigation history (so only backwards and forwards), or in the absolute scope of the app hierarchy which would make it a sort of Table of Contents view.
Now, the downside to this mechanism is that it doesn’t solve the habit of pressing the Home button in order to “escape” any sort of deep navigation hierarchy.My thought on that is that providing the user with some way in which they can leave, perhaps a new habit will be formed. This might only be discovered with some user testing.
The other issue is that it’s not easily discoverable. However, the tapping of the application bar (and double pressing the home button) are not easily discoverable actions, however, once learned, form an easy habit.