Programmatically, how does this application detect that a program is ready for input

Question

I need to build a small C# application which measures start up times for a definable application. I have found this free tool:

http://www.passmark.com/products/appti

Answer 1

You can call

WaitForInputIdle( ProcessInfo.hProcess, INFINITE );

Waits until the specified process has finished processing its initial input and is waiting for user input with no input pending, or until the time-out interval has elapsed.

http://msdn.microsoft.com/en-us/library/windows/desktop/ms687022(v=vs.85).aspx

http://www.codeproject.com/Articles/137/Sending-a-message-to-the-Main-Frame-Window-of-Anot