GetAltTabInfoW

// USER32.dll  (Unicode / -W)
#include <windows.h>

BOOL GetAltTabInfoW(
    HWND hwnd,   // optional
    INT iItem,
    ALTTABINFO* pati,
    LPWSTR pszItemText,   // optional
    DWORD cchItemText
);

<DllImport("USER32.dll", CharSet:=CharSet.Unicode, SetLastError:=True, ExactSpelling:=True)>
Public Shared Function GetAltTabInfoW(
    hwnd As IntPtr,   ' HWND optional
    iItem As Integer,   ' INT
    pati As IntPtr,   ' ALTTABINFO* in/out
    <MarshalAs(UnmanagedType.LPWStr)> pszItemText As System.Text.StringBuilder,   ' LPWSTR optional, out
    cchItemText As UInteger   ' DWORD
) As Boolean
End Function

' hwnd : HWND optional
' iItem : INT
' pati : ALTTABINFO* in/out
' pszItemText : LPWSTR optional, out
' cchItemText : DWORD
Declare PtrSafe Function GetAltTabInfoW Lib "user32" ( _
    ByVal hwnd As LongPtr, _
    ByVal iItem As Long, _
    ByVal pati As LongPtr, _
    ByVal pszItemText As LongPtr, _
    ByVal cchItemText As Long) As Long
' Unicode(W): 文字列は ByVal As LongPtr とし StrPtr(unicodeStr) を渡す
' VBA7前提(PtrSafe)。32bit Office では LongPtr→Long。Integer=16bit / Long=32bit / LongLong=64bit。

import ctypes
from ctypes import wintypes

GetAltTabInfoW = ctypes.windll.user32.GetAltTabInfoW
GetAltTabInfoW.restype = wintypes.BOOL
GetAltTabInfoW.argtypes = [
    wintypes.HANDLE,  # hwnd : HWND optional
    ctypes.c_int,  # iItem : INT
    ctypes.c_void_p,  # pati : ALTTABINFO* in/out
    wintypes.LPWSTR,  # pszItemText : LPWSTR optional, out
    wintypes.DWORD,  # cchItemText : DWORD
]
# GetLastError: use ctypes.GetLastError() (or ctypes.WinDLL(use_last_error=True))

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('USER32.dll')
GetAltTabInfoW = Fiddle::Function.new(
  lib['GetAltTabInfoW'],
  [
    Fiddle::TYPE_VOIDP,  # hwnd : HWND optional
    Fiddle::TYPE_INT,  # iItem : INT
    Fiddle::TYPE_VOIDP,  # pati : ALTTABINFO* in/out
    Fiddle::TYPE_VOIDP,  # pszItemText : LPWSTR optional, out
    -Fiddle::TYPE_INT,  # cchItemText : DWORD
  ],
  Fiddle::TYPE_INT)
# Wide strings: pass str.encode("UTF-16LE") + "\x00\x00"

#[link(name = "user32")]
extern "system" {
    fn GetAltTabInfoW(
        hwnd: *mut core::ffi::c_void,  // HWND optional
        iItem: i32,  // INT
        pati: *mut ALTTABINFO,  // ALTTABINFO* in/out
        pszItemText: *mut u16,  // LPWSTR optional, out
        cchItemText: u32  // DWORD
    ) -> i32;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[return: MarshalAs(UnmanagedType.Bool)]
[DllImport("USER32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
public static extern bool GetAltTabInfoW(IntPtr hwnd, int iItem, IntPtr pati, [MarshalAs(UnmanagedType.LPWStr)] System.Text.StringBuilder pszItemText, uint cchItemText);
"@
$api = Add-Type -MemberDefinition $sig -Name 'USER32_GetAltTabInfoW' -Namespace Win32 -PassThru
# $api::GetAltTabInfoW(hwnd, iItem, pati, pszItemText, cchItemText)

#uselib "USER32.dll"
#func global GetAltTabInfoW "GetAltTabInfoW" wptr, wptr, wptr, wptr, wptr
; GetAltTabInfoW hwnd, iItem, varptr(pati), varptr(pszItemText), cchItemText   ; 戻り値は stat
; hwnd : HWND optional -> "wptr"
; iItem : INT -> "wptr"
; pati : ALTTABINFO* in/out -> "wptr"
; pszItemText : LPWSTR optional, out -> "wptr"
; cchItemText : DWORD -> "wptr"
; ※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 GetAltTabInfoW "GetAltTabInfoW" sptr, int, var, var, int
; res = GetAltTabInfoW(hwnd, iItem, pati, pszItemText, cchItemText)
; hwnd : HWND optional -> "sptr"
; iItem : INT -> "int"
; pati : ALTTABINFO* in/out -> "var"
; pszItemText : LPWSTR optional, out -> "var"
; cchItemText : DWORD -> "int"
; ※出力/バッファ引数は var 方式(変数を直接渡す)。varptr 方式にも切替可。

; BOOL GetAltTabInfoW(HWND hwnd, INT iItem, ALTTABINFO* pati, LPWSTR pszItemText, DWORD cchItemText)
#uselib "USER32.dll"
#cfunc global GetAltTabInfoW "GetAltTabInfoW" intptr, int, var, var, int
; res = GetAltTabInfoW(hwnd, iItem, pati, pszItemText, cchItemText)
; hwnd : HWND optional -> "intptr"
; iItem : INT -> "int"
; pati : ALTTABINFO* in/out -> "var"
; pszItemText : LPWSTR optional, out -> "var"
; cchItemText : DWORD -> "int"
; ※出力/バッファ引数は var 方式(変数を直接渡す)。varptr 方式にも切替可。

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

var (
	user32 = windows.NewLazySystemDLL("USER32.dll")
	procGetAltTabInfoW = user32.NewProc("GetAltTabInfoW")
)

// hwnd (HWND optional), iItem (INT), pati (ALTTABINFO* in/out), pszItemText (LPWSTR optional, out), cchItemText (DWORD)
r1, _, err := procGetAltTabInfoW.Call(
	uintptr(hwnd),
	uintptr(iItem),
	uintptr(pati),
	uintptr(pszItemText),
	uintptr(cchItemText),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // BOOL

function GetAltTabInfoW(
  hwnd: THandle;   // HWND optional
  iItem: Integer;   // INT
  pati: Pointer;   // ALTTABINFO* in/out
  pszItemText: PWideChar;   // LPWSTR optional, out
  cchItemText: DWORD   // DWORD
): BOOL; stdcall;
  external 'USER32.dll' name 'GetAltTabInfoW';

result := DllCall("USER32\GetAltTabInfoW"
    , "Ptr", hwnd   ; HWND optional
    , "Int", iItem   ; INT
    , "Ptr", pati   ; ALTTABINFO* in/out
    , "Ptr", pszItemText   ; LPWSTR optional, out
    , "UInt", cchItemText   ; DWORD
    , "Int")   ; return: BOOL

●GetAltTabInfoW(hwnd, iItem, pati, pszItemText, cchItemText) = DLL("USER32.dll", "bool GetAltTabInfoW(void*, int, void*, char*, dword)")
# 呼び出し: GetAltTabInfoW(hwnd, iItem, pati, pszItemText, cchItemText)
# hwnd : HWND optional -> "void*"
# iItem : INT -> "int"
# pati : ALTTABINFO* in/out -> "void*"
# pszItemText : LPWSTR optional, out -> "char*"
# cchItemText : DWORD -> "dword"
# 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)。
# ※-W(Unicode)関数。なでしこ1はANSIのため -A 版の利用を推奨。