public static IEnumerable <IntPtr> EnumerateProcessWindowHandles(int processId)
{
var handles = new List <IntPtr>();
foreach (ProcessThread thread in Process.GetProcessById(processId).Threads)
{
User32Interop.EnumThreadWindows(thread.Id, (hWnd, lParam) => {
handles.Add(hWnd);
return(true);
}, IntPtr.Zero);
}
return(handles);
}