Arrange Word Windows Horizontal @ VBA (Word Only)

ModuleEnumWindows.bas

Private Declare Function IsWindowVisible Lib "user32" _
   (ByVal hWnd&) As Long
Private Declare Function GetWindowText Lib "user32" Alias "GetWindowTextA" _
   (ByVal hWnd As Long, ByVal lpString As String, ByVal cch As Long) As Long
Private Declare Function GetClassName Lib "user32" Alias "GetClassNameA" _
   (ByVal hWnd As Long, ByVal lpClassName As String, _
    ByVal nMaxCount As Long) As Long
Private Declare Function FindWindow Lib "user32.dll" Alias "FindWindowA" _
    (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Private Declare Function EnumWindows Lib "user32" _
    (ByVal lpEnumFunc As Long, ByVal lParam As Long) As Long
       
Dim windowHandles As Variant 'EnumWindowsProcで取得したハンドルの格納用
Private Function EnumWindowsProc _
        (ByVal handle As Long, ByVal lParam As Object) As Long
    If IsWindowVisible(handle) Then
        windowHandles.Add (handle)
    End If
    EnumWindowsProc = True
End Function

' Word (ClassName: OpusApp)のウィンドウハンドルをまとめて取得
Public Function GetWindowHandlesOfWord() As Variant
    Set windowHandles = New Collection
    Call EnumWindows(AddressOf EnumWindowsProc, ByVal 0&) 'Long型を明示 ←末尾&で
    Set windowHandles = FilterByClassName(windowHandles, "OpusApp")
    Set GetWindowHandlesOfWord = windowHandles
End Function

Private Function FilterByClassName(handles, className As String) As Variant
    Dim output As Variant
    Set output = New Collection
    Dim handle

    For Each handle In handles
        Call AddHandleIf(output, handle, className)
    Next
    
    Set FilterByClassName = output
End Function

Private Sub AddHandleIf(ByRef output, handle, className)
    Dim strClassName As String * 100
    Dim gettedClassName As String 'strClassNameは100文字に固定されているため。無駄な空白を除いた文字列を格納するための変数
    
    GetClassName handle, strClassName, Len(strClassName)
    gettedClassName = Trim(Left(strClassName, InStr(1, strClassName, vbNullChar) - 1))
    If gettedClassName = className Then
        output.Add (handle)
    End If
End Sub

ModuleTileHorizontal.bas

Option Explicit

Private Declare Function MoveWindow Lib "user32" _
    (ByVal hWnd As Long, _
    ByVal x As Long, ByVal y As Long, _
    ByVal nWidth As Long, ByVal nHeight As Long, _
    ByVal bRepaint As Long) As Long
Private Declare Function ShowWindow Lib "user32" _
    (ByVal hWnd As Long, ByVal nCmdShow As Integer) As Boolean
Const SW_NORMAL = 1

Declare Function SystemParametersInfo Lib "user32" Alias "SystemParametersInfoA" ( _
    ByVal uAction As Long, ByVal uParam As Long, _
    ByRef lpvParam As Any, ByVal fuWinIni As Long) As Long
Public Type RECT
    Left   As Long
    Top    As Long
    Right As Long
    Bottom As Long
End Type
Public Const SPI_GETWORKAREA = 48

Sub TileHorizontal()
    Dim ttlHeight As Integer  'Word画面の横幅
    Dim ttlWidth As Integer   'Word画面の縦幅
    Dim indivWidth As Integer  '個別のファイルの横幅
    Dim i As Integer: i = 1 '※Forをやめて、For eachを使うため
    Dim nDoc As Integer '開かれているファイルの数
    
    '開かれているファイルの数を取得
    nDoc = Documents.count
    
    If nDoc < 1 Then Exit Sub
 
    ' ※　作業領域（タスクバーを除くディスプレイ領域）を計算
    Dim workArea As RECT
    Call SystemParametersInfo(SPI_GETWORKAREA, 0, workArea, 0)
    ttlWidth = workArea.Right - workArea.Left
    ttlHeight = workArea.Bottom - workArea.Top

    Dim windowHandles As New Collection
    Dim windowHandle As Variant '※For eachで代入する為

    Set windowHandles = GetWindowHandlesOfWord
    
    '個別ファイルの横幅の設定（縦幅は画面全幅）※Documents.CountはWord2010で誤動作する場合あり
    indivWidth = ttlWidth / windowHandles.count
    
    For Each windowHandle In windowHandles
        Call ShowWindow(windowHandle, SW_NORMAL)
        
        '※　有効画面領域の左・上端を基準に
        Call MoveWindow(windowHandle, _
            indivWidth * (i - 1) + workArea.Left, _
            0 + workArea.Top, _
            indivWidth, _
            ttlHeight, _
            1)
            
        i = i + 1
    Next
End Sub