DDSmoothmenu not working with keyboard (arrow key) - css

Question

ddsmoothmenu not working with arrow keys on the keyboard.
when li list is so long this goes below the page so unable to click on li. So how do I handle this issue?
ddsmoothmenu.init({
mainmenuid: "divMenu", //menu DIV id
orientation: 'h', //Horizontal or vertical menu: Set to "h" or "v"
classname: 'ddsmoothmenu', //class added to menu's outer DIV
contentsource: "markup" //"markup" or ["container_id", "path_to_menu_file"]
})
<div align="left" id="tdmenu">
<table cellpadding="0" cellspacing="0" border="0" width="100%">
<tr>
<td width="75%">
<div id="divMenu" class="ddsmoothmenu">
<ul>
<li>
Home
</li>
<asp:Literal runat="server" ID="ltMenu"></asp:Literal>
<li runat="server" id="divProSupportTicket" visible="false">
<a href="javascript:showWindow('supportticket.aspx',900,600,100)">
<img src="images/support.png" alt="Software Support Form" height="20" title="Software Support Form" />
</a>
</li>
<li>
<div id="HelpIcon" style="border: solid 1px gray; background-color: #4C83F8; border-radius: 50%; cursor: pointer; width: 25px; margin-left: 10px; margin-top: 2px;" title="Help Information" onclick="showHelp('home_Vehicle');">
<span style="font-size: 20px; color: White; font-weight: bold; padding: 0px 7px 0px 7px;">
<i>i</i>
</span>
</div>
</li>
<li runat="server" id="liCompanyContacts" visible="false"></li>
</ul>
</div>
</td>
</tr>
</table>
</div>