用iFrame遮挡DropDownList的方法

方法：在<div></div>中加入<iframe></ifame>

實例：<div >
                    <iframe style="Z-INDEX:-1;WIDTH:100%;POSITION:absolute;HEIGHT:100%">
        </iframe>
                    <a href="../cs/csAnnounceContent.aspx?BulletinID=BLT-08080800003" target="_blank">
                        <img src="../Images/connectWay.jpg" border="0" />
                    </a>                    
               </div>