How to get the Title Bar Text of a EXE by its Process Id using C#

[DllImport("user32", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
private extern static bool EnumThreadWindows(int threadId, EnumWindowsProc callback, IntPtr lParam);
[DllImport("user32", SetLastError = true, CharSet = CharSet.Auto)]
private extern static int GetWindowText(IntPtr hWnd, StringBuilder text, int maxCount);
private delegate bool EnumWindowsProc(IntPtr hWnd, IntPtr lParam);


public IEnumerable<string> GetWindowText(Process p)
    {
    List<string> titles = new List<string>();
    foreach (ProcessThread t in p.Threads)
        {
        EnumThreadWindows(t.Id, (hWnd, lParam) =>
        {
            StringBuilder text = new StringBuilder(200);
            GetWindowText(hWnd, text, 200);
            titles.Add(text.ToString());
            return true;
        }, IntPtr.Zero);
        }
    return titles;
    }