App Switcher with Screen Capture Utility

I need a simple and small C# background application that enables the user to use a hot-key to switch between 2-4 different applications. Also, each time the application is switched, a PNG image screenshot of a defined screen region is saved and written to a file. Please... Only developers respond - no agencies. You must read the attached spec and respond with information that indicates the approach you will use to complete this application. Generic responses will be deleted.