On example page is not problem, but on my page i'm using DIV, and set on style visibility of DIV tag "hidden" and "" (none)
(Some time is problem, some time is OK)
<div id="aaa" style="position: absolute; background-color:White; border:solid 1px #124F97; z-index:1000 ; left: 17px; top: 178px;visibility:hidden">
<ce:editor id="EditNoiDung" runat="server" allowpastehtml="true" autoconfigure="Full_noform"
breakelement="Br" TemplateItemList="Save,ForeColor,Bold,Italic,Underline,JustifyLeft,JustifyCenter,JustifyRight,InsertUnorderedList,Separator,Indent, Outdent, insertcustombutonhere,ImageGalleryByBrowsing,table"
disableautoformatting="True" enablestripscripttags="false" enabletheming="False"
enableviewstate="False" height="352px" removeservernamesfromurl="False" removetbodytag="true" securitypolicyfile="NewIdeas.config"
showpreviewmode="False" width="465px">
<FrameStyle BackColor="White" BorderColor="#DDDDDD" BorderStyle="Solid" BorderWidth="1px"
CssClass="CuteEditorFrame" Height="100%" Width="100%" />
</ce:editor>
</div>
<script type="text/javascript">
function Showdata(){
tempDivlistnews = document.getElementById('aaa');
tempDivlistnews.style.visibility="";
EditorData = document.getElementById('<%=EditNoiDung.ClientID%>');
EditorData.setHTML("Thu Nghiem");
}
function HideData(){
tempDivlistnews = document.getElementById('aaa');
tempDivlistnews.style.visibility="hidden";
}
</script>