<% Html.Obout(new ListBox("ListBox1")
    {   
        Width = Unit.Pixel(300),
    }); %>
    
    <% Html.Obout(new OboutCheckBox("OboutCheckBox1")
    {
        Text = "Get Selected Item",
        OnClientClick = "return getSelectedItem();"
    }); %>	   
    
    

    @Html.Obout(new ListBox("ListBox1")
    {   
        Width = Unit.Pixel(300),
    })
    
    @Html.Obout(new OboutCheckBox("OboutCheckBox1")
    {
        Text = "Get Selected Item",
        OnClientClick = "return getSelectedItem();"
    })
    
    

    function getSelectedItem() {
        if (ListBox1.selectedIndex() != -1) {
            alert('Selected item: ' + ListBox1.options[ListBox1.selectedIndex()].text);
        } else {
            alert('No selected item.');
        }

        return false;
    }