在ExtJS网格中添加下侧到侧滚动条

下面是我的两个网格——它们是ExtJs网格,但是我们用vb.net代码包装声明:

Dim VehicleOptionsGrid As New Framework.WebControls.Grids.Grid
    With VehicleOptionsGrid
        .ID = "VehicleOptionsGrid"
        .Title = "Vehicle Options"
        .Toolbar.UseDefaultButtons = False        
        .Mode = Grids.Grid.GridMode.Control        
        .Panel.Border = False
        .Panel.Style = "border-width:1px;margin-bottom:5px"
        .Ref = "../../../../VehicleOptionsGrid"
        .Editable = True
        With .Columns.Add("IsSelected", "Selection", Framework.WebControls.Grids.Grid.ColumnDataType.Boolean)
            .Renderer = "renderVehicleCheckbox"
        End With
        .Columns.Add("CollateralId", "").Hidden = True
        .Columns.Add("OptionId", "OptionId").Hidden =True         
        .Columns.Add("OptionName", "Name").Width = 400
        .GridHeight = 400
        .DataBind()

        ViewResponse.AddScript(.ToString(False))
        ViewResponse.AddScript("VehicleOptionsGrid.grid.addListener('cellclick', changeOptionStatus);")
    End With

    Dim VehicleResultsGrid As New Framework.WebControls.Grids.Grid
    With VehicleResultsGrid
        .ID = "VehicleResultsGrid"
        .Title = "Results"
        .Toolbar.UseDefaultButtons = False
        .Mode = Grids.Grid.GridMode.Control
        .Panel.Border = False
        .Panel.Style = "border-width:1px;margin-bottom:5px"
        .Ref = "../../../../VehicleResultsGrid"        
        .Columns.Add("CollateralId", "").Hidden = True
        .Columns.Add("ValueType", "Value Type")
        .Columns.Add("ValueAmount", "Amount", Framework.WebControls.Grids.Grid.ColumnDataType.Money).Width = 400
        .GridHeight = 400
        .DataBind()

        ViewResponse.AddScript(.ToString(False))
    End With

使用javascript,是否可以在这些网格中添加底部滚动条?似乎我们没有包装好的命令来做。。。