GetTopWindow

// USER32.dll
#include <windows.h>

HWND GetTopWindow(
    HWND hWnd   // optional
);

<DllImport("USER32.dll", SetLastError:=True, ExactSpelling:=True)>
Public Shared Function GetTopWindow(
    hWnd As IntPtr   ' HWND optional
) As IntPtr
End Function

' hWnd : HWND optional
Declare PtrSafe Function GetTopWindow Lib "user32" ( _
    ByVal hWnd As LongPtr) As LongPtr
' VBA7前提(PtrSafe)。32bit Office では LongPtr→Long。Integer=16bit / Long=32bit / LongLong=64bit。

import ctypes
from ctypes import wintypes

GetTopWindow = ctypes.windll.user32.GetTopWindow
GetTopWindow.restype = ctypes.c_void_p
GetTopWindow.argtypes = [
    wintypes.HANDLE,  # hWnd : HWND optional
]
# GetLastError: use ctypes.GetLastError() (or ctypes.WinDLL(use_last_error=True))

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('USER32.dll')
GetTopWindow = Fiddle::Function.new(
  lib['GetTopWindow'],
  [
    Fiddle::TYPE_VOIDP,  # hWnd : HWND optional
  ],
  Fiddle::TYPE_VOIDP)

#[link(name = "user32")]
extern "system" {
    fn GetTopWindow(
        hWnd: *mut core::ffi::c_void  // HWND optional
    ) -> *mut core::ffi::c_void;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("USER32.dll", SetLastError = true)]
public static extern IntPtr GetTopWindow(IntPtr hWnd);
"@
$api = Add-Type -MemberDefinition $sig -Name 'USER32_GetTopWindow' -Namespace Win32 -PassThru
# $api::GetTopWindow(hWnd)

#uselib "USER32.dll"
#func global GetTopWindow "GetTopWindow" sptr
; GetTopWindow hWnd   ; 戻り値は stat
; hWnd : HWND optional -> "sptr"
; ※HSP3.7は #func のため戻り値はシステム変数 stat に格納されます。

#uselib "USER32.dll"
#cfunc global GetTopWindow "GetTopWindow" sptr
; res = GetTopWindow(hWnd)
; hWnd : HWND optional -> "sptr"

; HWND GetTopWindow(HWND hWnd)
#uselib "USER32.dll"
#cfunc global GetTopWindow "GetTopWindow" intptr
; res = GetTopWindow(hWnd)
; hWnd : HWND optional -> "intptr"

import (
	"golang.org/x/sys/windows"
	"unsafe"
)

var (
	user32 = windows.NewLazySystemDLL("USER32.dll")
	procGetTopWindow = user32.NewProc("GetTopWindow")
)

// hWnd (HWND optional)
r1, _, err := procGetTopWindow.Call(
	uintptr(hWnd),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // HWND

function GetTopWindow(
  hWnd: THandle   // HWND optional
): THandle; stdcall;
  external 'USER32.dll' name 'GetTopWindow';

result := DllCall("USER32\GetTopWindow"
    , "Ptr", hWnd   ; HWND optional
    , "Ptr")   ; return: HWND

●GetTopWindow(hWnd) = DLL("USER32.dll", "void* GetTopWindow(void*)")
# 呼び出し: GetTopWindow(hWnd)
# hWnd : HWND optional -> "void*"
# なでしこ1は32bit・ANSI(Shift_JIS)。文字列=char*(ANSI)、ポインタ/ハンドル=void*(4byte)。