how to display list of dropdown when mouse over

<asp:dropdownlist runat="server" id="cbSort" cssclass="dropDownList" autopostback="true" onselectedindexchanged="cbItemsPerPage_SelectedIndexChanged" width="155" xmlns:asp="#unknown">
                    <asp:listitem text="Title A-Z" value="1a" selected="True"></asp:listitem>
                    <asp:listitem text="Sub Type Z-A" value="7z"></asp:listitem>
                </asp:dropdownlist>

$('#MainContent_cbSort').hover(function(){
    $(this).attr('size', 2);
},function(){
    $(this).removeAttr('size');
});