How to use customized screen instead of default start screen in Android?

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http://stackoverflow.com – I 'am making an enterprise app, the user should be able to use only those applications which i provide him. My idea is overriding the default start screen with my custom layout with the app icons, of only those apps which i provide to the user. I will disable home, menu back and search buttons in the starting screen. Even if the user presses home button he should be redirected to my custom screen which contains icons. I have seen an application which has achieved this without rooting the device. Here is the link for that app. I just want to know how should i send the starting screen into ba (HowTos)