What exactly is a top-level window in win32 programming?

Question

I don't quite understand what the difference between a window that I create via CreateWindowEx and a "top-level" window.

What is a top level window in win32 programming?

Answer 1

The MSDN entry About Windows offers the following definition:

A window that has no parent, or whose parent is the desktop window, is called a top-level window.

A more practical explanation is given in the blog post A window can have a parent or an owner but not both:

A window can be created as a child window (WS_CHILD set) or a top-level window (WS_CHILD not set).

Answer 2

A top-level window is a window that is not a child window, or has no parent window (which is the same as having the "desktop window" as a parent).