If you have ever used an Android device, you have probably noticed that it works quite differently from many other operating systems. For example, you are using an application—say you're checking what people are doing on Facebook. Then you get an e-mail notification and you tap the e-mail icon to read it. Midway through reading the e-mail, you might get a Twitter notification and because you're waiting on important news from someone you follow, you interrupt your e-mail reading and change the app to Twitter with a touch.

After reading the tweet, you fancy a game of Angry Birds, but midway through the first daring fling, you suddenly remember that Facebook post. So you quit Angry Birds and tap the Facebook icon.

Then you resume Facebook, probably at the same point you left it. You could have resumed reading the e-mail, decided to reply to the tweet, or started an entirely new app. All this backwards and forwards takes quite a lot of management on the part of...