Hi Kenneth,
sure, with this code I can reproduce it in IE10 and CHROME. But before you load the page, you have to clear your browser cache, then the error message appears.
The error message comes with JQUERY UI TABS and also AJAX TOOLKIT TABS, when having more than one tab and more than one editor.
Thanks in advance for your fast help or fix for this!
<%@ Register TagPrefix="RTE" Namespace="RTE" Assembly="RichTextEditor" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
<link rel="stylesheet" href="http://code.jquery.com/ui/1.10.3/themes/smoothness/jquery-ui.css" />
<script src="http://code.jquery.com/jquery-1.9.1.js"></script>
<script src="http://code.jquery.com/ui/1.10.3/jquery-ui.js"></script>
<script>
$(function () {
$("#tabs").tabs();
});
</script>
</head>
<body>
<form id="form1" runat="server">
<div id="tabs">
<ul>
<li><a href="#tabs-1">Nunc tincidunt</a></li>
<li><a href="#tabs-2">Proin dolor</a></li>
<li><a href="#tabs-3">Aenean lacinia</a></li>
</ul>
<div id="tabs-1">
<div><RTE:Editor id="Editor1" ShowStatistics="False" ShowZoomView="False" runat="server" Language="de-DE" AutoParseClasses="False" AllowScriptCode="true" PasteMode="PasteText" EnterKeyTag="DIV" ResizeMode="Default" URLType="SiteRelative" /></div>
<div><RTE:Editor id="Editor2" ShowStatistics="False" ShowZoomView="False" runat="server" Language="de-DE" AutoParseClasses="False" AllowScriptCode="true" PasteMode="PasteText" EnterKeyTag="DIV" ResizeMode="Default" URLType="SiteRelative" /></div>
<div><RTE:Editor id="Editor10" ShowStatistics="False" ShowZoomView="False" runat="server" Language="de-DE" AutoParseClasses="False" AllowScriptCode="true" PasteMode="PasteText" EnterKeyTag="DIV" ResizeMode="Default" URLType="SiteRelative" /></div>
<div><RTE:Editor id="Editor11" ShowStatistics="False" ShowZoomView="False" runat="server" Language="de-DE" AutoParseClasses="False" AllowScriptCode="true" PasteMode="PasteText" EnterKeyTag="DIV" ResizeMode="Default" URLType="SiteRelative" /></div>
<div><RTE:Editor id="Editor3" ShowStatistics="False" ShowZoomView="False" runat="server" Language="de-DE" AutoParseClasses="False" AllowScriptCode="true" PasteMode="PasteText" EnterKeyTag="DIV" ResizeMode="Default" URLType="SiteRelative" /></div>
</div>
<div id="tabs-2">
<div><RTE:Editor id="Editor4" ShowStatistics="False" ShowZoomView="False" runat="server" Language="de-DE" AutoParseClasses="False" AllowScriptCode="true" PasteMode="PasteText" EnterKeyTag="DIV" ResizeMode="Default" URLType="SiteRelative" /></div>
<div><RTE:Editor id="Editor5" ShowStatistics="False" ShowZoomView="False" runat="server" Language="de-DE" AutoParseClasses="False" AllowScriptCode="true" PasteMode="PasteText" EnterKeyTag="DIV" ResizeMode="Default" URLType="SiteRelative" /></div>
<div><RTE:Editor id="Editor12" ShowStatistics="False" ShowZoomView="False" runat="server" Language="de-DE" AutoParseClasses="False" AllowScriptCode="true" PasteMode="PasteText" EnterKeyTag="DIV" ResizeMode="Default" URLType="SiteRelative" /></div>
<div><RTE:Editor id="Editor13" ShowStatistics="False" ShowZoomView="False" runat="server" Language="de-DE" AutoParseClasses="False" AllowScriptCode="true" PasteMode="PasteText" EnterKeyTag="DIV" ResizeMode="Default" URLType="SiteRelative" /></div>
<div><RTE:Editor id="Editor6" ShowStatistics="False" ShowZoomView="False" runat="server" Language="de-DE" AutoParseClasses="False" AllowScriptCode="true" PasteMode="PasteText" EnterKeyTag="DIV" ResizeMode="Default" URLType="SiteRelative" /></div>
</div>
<div id="tabs-3">
<div><RTE:Editor id="Editor7" ShowStatistics="False" ShowZoomView="False" runat="server" Language="de-DE" AutoParseClasses="False" AllowScriptCode="true" PasteMode="PasteText" EnterKeyTag="DIV" ResizeMode="Default" URLType="SiteRelative" /></div>
<div><RTE:Editor id="Editor8" ShowStatistics="False" ShowZoomView="False" runat="server" Language="de-DE" AutoParseClasses="False" AllowScriptCode="true" PasteMode="PasteText" EnterKeyTag="DIV" ResizeMode="Default" URLType="SiteRelative" /></div>
<div><RTE:Editor id="Editor14" ShowStatistics="False" ShowZoomView="False" runat="server" Language="de-DE" AutoParseClasses="False" AllowScriptCode="true" PasteMode="PasteText" EnterKeyTag="DIV" ResizeMode="Default" URLType="SiteRelative" /></div>
<div><RTE:Editor id="Editor15" ShowStatistics="False" ShowZoomView="False" runat="server" Language="de-DE" AutoParseClasses="False" AllowScriptCode="true" PasteMode="PasteText" EnterKeyTag="DIV" ResizeMode="Default" URLType="SiteRelative" /></div>
<div><RTE:Editor id="Editor9" ShowStatistics="False" ShowZoomView="False" runat="server" Language="de-DE" AutoParseClasses="False" AllowScriptCode="true" PasteMode="PasteText" EnterKeyTag="DIV" ResizeMode="Default" URLType="SiteRelative" /></div>
</div>
</form>
</body>
</html>