'自前のウィンドウプロシージャ
Public Function MainFormWindowProc(ByVal hWnd As Long, ByVal uMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
    Dim nKeys As Long
    Dim nDelta As Long
    Dim nX As Long
    Dim nY As Long
    Dim sbiInfo As SCROLLINFO
    
    'Debug.Print Hex(hwnd), Hex(uMsg), Hex(wParam), Hex(lParam)     'すべてのメッセージを表示(結構楽しい(^_^))
    
    On Error GoTo ErrorHandle
    
    Select Case uMsg
    Case WM_MOUSEWHEEL
        Debug.Print "WM_MOUSEWHEEL"
        nKeys = LOWORD(wParam)
        nDelta = HIWORD(wParam)
        nX = LOWORD(lParam)
        nY = HIWORD(lParam)
'
        sbiInfo.cbSize = LenB(sbiInfo)
        sbiInfo.fMask = SIF_ALL
        If 0 <> GetScrollInfo(hWnd, SB_VERT, sbiInfo) Then
            Call SendMessageByNum(hWnd, WM_VSCROLL, IIf(nDelta > 0, SB_LINEUP, SB_LINEDOWN), 0)
        End If
    
    End Select
    
    'デフォルトのウィンドウプロシージャを呼び出す
    MainFormWindowProc = CallWindowProc(lngDefaultProc, hWnd, uMsg, wParam, lParam)
    
    Exit Function
    
ErrorHandle:
    Debug.Print Err.Number & " : " & Err.Description
    Resume Next
End Function