internal static bool TrySetFormChildWindowStyle(Form form)
        {
            long newStyle = (long)USER32.GetWindowLongPtr(form.Handle, GWL_STYLE);

            if (newStyle == 0)
            {
                return(false);
            }
            newStyle = (newStyle | WS_CHILD) & ~WS_POPUP;
            return(USER32.SetWindowLongPtr(form.Handle, GWL_STYLE, (IntPtr)newStyle) != IntPtr.Zero);
        }
        private const uint SRCCOPY        = 0xCC0020;   // flag for copying a source rectangle directly to a destination rectangle

        internal static void SetFormOwner(Form form, IntPtr ownerHandle)
        {
            USER32.SetWindowLongPtr(form.Handle, GWLP_HWNDPARENT, ownerHandle);
        }