[pax]

public static List<IntPtr> FindWindowsByClassInProcess(string windowClassName, string processName)
        {
            var windows = new List<IntPtr>();
            var processWindowHandles = EnumerateProcessWindowHandles(
                Process.GetProcessesByName("explorer").First().Id);

            foreach (var handle in processWindowHandles)
            {
                if (GetWindowClassName(handle).StartsWith(windowClassName))
                {
                    windows.Add(handle);
                }
            }

            return windows;
        }