Get all window handles for a process

Question

Using Microsoft Spy++, I can see that the following windows that belong to a process:

Process XYZ window handles, displayed in tree form just like Spy++ gives me:

A
  B
  C
     D
E
F
  G
  H
  I
  J
     K

I can get the process, and the MainWindowHandle property points to the handle for window F. If I enumerate the child windows using I can get a list of window handles for G through K, but I can't figure out how to find the window handles for A through D. How can I enumerate windows that are not children of the handle specified by MainWindowHandle of the Process object?

To enumerate I'm using the win32 call:

[System.Runtime.InteropServices.DllImport(strUSER32DLL)]
            public static extern int EnumChildWindows(IntPtr hWnd, WindowCallBack pEnumWindowCallback, int iLParam);

Answer 1

Pass IntPtr.Zero as hWnd to get every root window handle in the system.

You can then check the windows' owner process by calling GetWindowThreadProcessId.

Answer 2

You can use EnumWindows to get every top-level window, and then filter the results based on GetWindowThreadProcessId.