Hi, I need a small prototype of Android app which will do following: A user clicks on our application and it starts and works in background (no UI). As soon as user clicks on any other application in the launcher, our application should show "Hello world" screen with OK button. It can show it prior other application UI will displayed or on top of other application UI. I think (but I am not sure) that following API can be used to track that new activity is launched with android.intent.action.MAIN action and android.intent.category.DEFAULT or android.intent.category.LAUNCHER category. http://developer.android.com/reference/android/app/Instrumentation.ActivityMonitor.html Regards, Victor Legal: 1) I require complete and fully-functional working program(s) in executable form as well as complete source code of all work done (so that I may modify it in the future). 2) Deliverables must be in ready-to-run condition as follows (depending on the nature of the deliverables): 2b) Any website server-side deliverables must be installed by the worker in ready-to-run condition in the employer's environment. 2c) Any website server-side deliverables must be provided with complete instructions and assistance so that the employer may install them in ready-to-run condition in the employer's environment. 2d) Any website server-side deliverables must be installed as described elsewhere by the employer. 2e) If there are any server-side deliverables (intended to only exist in one place in the employer's environment) then they must be installed by the worker in ready-to-run condition (unless specified elsewhere by the employer). 2f) All other software (including but not limited to any desktop software or software the employer intends to distribute) must include a software installation package that will install the software in ready-to-run condition on the platform(s) specified in this project (unless specified elsewhere by the employer). 3) All deliverables will be considered 'work made for hire' under U.S. Copyright law. Employer will receive exclusive and complete copyrights to all work purchased. 3b) No part of the deliverable may contain any copyright restricted 3rd party components (including GPL, GNU, Copyleft, etc.) unless all copyright ramifications are explained AND AGREED TO by the employer on the site per the worker's 'Worker Legal Agreement'.