You can have
iPhone home button on screen for returning you to the phone's default screen. No need any app. Its can also be used same with iPhone's Home button, the button at the bottom center of the phone. Your iPhone have to upgrade to iOS5 for this feature.
Go to Setting >> General >> Accessibility >> Assistive Touch, select ON. Your iPhone will have a
circle on the bottom right of the screen. Tap the circle for iPhone home button on screen will show.
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Assistive Touch allows you to use iPhone if you have difficult touching the screen or if you require an adaptive accessory." The iPhone home button is the most commonly used. However, I think its may not easy to broken and not working, but this feature will reduce number of iPhone Home Button use. Except, when Sleep mode cannot use
iPhone home button on screen.
