1. API 的宣告：

    Const LB_SETHORIZONTALEXTENT = &H194
    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

 2. 程式范例：
   ' List1 为 ListBox 的名称
   Call SendMessage(List1.hwnd, LB_SETHORIZONTALEXTENT, _
        水平卷动轴的宽度, ByVal 0&)

 特别注意：以上的水平卷动轴宽度的单位是 pixel(像素)。