What API do I use to get notified when another application creates a new window - WindowsXP/C++?

I want to write a C++ application that will interact with an existing application (which I cannot modify). The idea is that the user will start my app, which in turn will start the existing app. The user will interact with the existing app, resulting in one or more new windows being created from the existing app.





How do I get notified when a new window is created and how do I get a handle to those new windows? When a new window is created, I will be creating a new thread to interact with it. The interactions will be things like bringing the window to the front when certain conditions occur, resizing, moving, etc. I don't need help with any of these interactions, just getting a handle to the new windows as they are created.

What API do I use to get notified when another application creates a new window - WindowsXP/C++?
Holy crap! Are you kidding?