Hi Comartis,
Please try the example page below, it works fine for me.
Focus on the text box, then click the button.
<%@ Page Language="C#" AutoEventWireup="true" %>
<%@ Register TagPrefix="CE" Namespace="CuteEditor" Assembly="CuteEditor" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<asp:TextBox ID="tb1" runat="server"></asp:TextBox>
<CE:Editor ID="Editor1" runat="server">
</CE:Editor>
<input type="button" value="Focus Editor" onclick="focusEditor()" />
</form>
</body>
</html>
<script>
function focusEditor()
{
var editor1=document.getElementById("<%= Editor1.ClientID %>");
editor1.FocusDocument();
}
</script>
Regards,
Ken