在VB6环境的代码窗口捕获滚轮消息

在VB6中，可以通过以下步骤来捕获滚轮消息：

1. 在窗体或控件的声明部分添加一个常量：

Private Const WM_MOUSEWHEEL As Long = &H20A

2. 在窗体或控件的代码部分添加一个消息处理程序：

Private Sub Form_MouseWheel(ByVal Shift As Integer, ByVal WheelDelta As Integer, ByVal X As Single, ByVal Y As Single)
    If WheelDelta > 0 Then
        '向上滚动
    Else
        '向下滚动
    End If
End Sub

3. 如果要在控件内捕获滚轮消息，还需要将控件的`MouseWheelEvent`属性设置为`True`，并将其`MouseWheel`事件与上面的消息处理程序关联：

Private Sub Text1_MouseWheel(ByVal OldScrollPos As Long, ByVal NewScrollPos As Long, ByVal Cancel As Integer)
    If NewScrollPos > OldScrollPos Then
        '向上滚动
    Else
        '向下滚动
    End If
End Sub

Private Sub Text1_MouseWheelEvent(ByVal Ctrl As Object, ByVal Cancel As Integer, ByVal MouseWheel As Integer)
    Cancel = True '取消控件的默认处理
    SendMessage Me.hWnd, WM_MOUSEWHEEL, MouseWheel * &H10000, 0 '发送消息给窗体
End Sub

注意：上面的代码中使用了`SendMessage`函数，该函数需要在模块中声明：

Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hWnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long