private static extern bool GetWindowPlacement(IntPtr hWnd, out WINDOWPLACEMENT lpwndpl);
public static string Save(Window window)
{
WINDOWPLACEMENT wp = new WINDOWPLACEMENT();
IntPtr hwnd = new WindowInteropHelper(window).Handle;
GetWindowPlacement(hwnd, out wp);
int size = Marshal.SizeOf(typeof(WINDOWPLACEMENT));
var buf = new byte[size];
IntPtr p = Marshal.AllocHGlobal(size);
Marshal.StructureToPtr(wp, p, true);
Marshal.Copy(p, buf, 0, size);
Marshal.FreeHGlobal(p);
return Convert.ToBase64String(buf);
}