RegisterStartupScript(string, string)

我编写了个脚本
<script type="text/javascript">
function mainThemeWordSelect()
{
window.open("ThemeWordSelect.aspx","_blank", "toolbar=no,resizable=yes,scrollbars=yes");
}
</script>
想让服务器控件LinkButton被点击时执行这脚本，后台代码这样写的
protected void lbMainTheme_Click(object sender, EventArgs e)
{
Page.RegisterStartupScript("sds", "<script language='javascript'>mainThemeWordSelect();<" + "/script>");

}
编译是正确的，可是发出这样的警告
警告 1 “System.Web.UI.Page.RegisterStartupScript(string, string)”已过时:“The recommended alternative is ClientScript.RegisterStartupScript(Type type, string key, string script). http://go.microsoft.com/fwlink/?linkid=14202” D:\Projects\ZYDB\SRC\GZZY\UI\Docum