})
	type Wndclassex struct {
		Size       uint32
		Style      uint32
		WndProc    uintptr
		ClsExtra   int32
		WndExtra   int32
		Instance   syscall.Handle
		Icon       syscall.Handle
		Cursor     syscall.Handle
		Background syscall.Handle
		MenuName   *uint16
		ClassName  *uint16
		IconSm     syscall.Handle
	}
	name := syscall.StringToUTF16Ptr("test_window")
	wc := Wndclassex{
		WndProc:   cb,

	// under standard cryptographic assumptions (see [Larsson] for examples).
	//
	// [Coron]: https://cs.nyu.edu/~dodis/ps/merkle.pdf
	// [Larsson]: https://web.archive.org/web/20040719170906/https://www.nada.kth.se/kurser/kth/2D1441/semteo03/lecturenotes/assump.pdf

	// Get 256 bits of entropy from rand.
	entropy := make([]byte, 32)
	if _, err := io.ReadFull(rand, entropy); err != nil {
		return nil, err
	}