Bug in RadMenu in IE8

2 posts, 1 answers
  1. wnl
    wnl avatar
    106 posts
    Member since:
    Aug 2007

    Posted 07 Sep 2010 Link to this post

    I'm using RadMenu. I have to change opacity of whole page. So I wrote a code:

    protected void Page_Load(object sender, EventArgs e)
            ClientScript.RegisterStartupScript(typeof(string), "DoDarker", "$('html').css('opacity', 0.7);", true);

    and an aspx file:

    <%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" %>
    <%@ Register Assembly="Telerik.Web.UI" Namespace="Telerik.Web.UI" TagPrefix="telerik" %>
    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
    <head runat="server">
        <script src="jquery-1.4.2.min.js" type="text/javascript"></script>
    <body style="background-color: Maroon;">
        <form id="form1" runat="server">
        <telerik:RadScriptManager ID="RadScriptManager1" runat="server">
            <telerik:RadMenu ID="RadMenu1" runat="server">
                    <telerik:RadMenuItem runat="server" Text="Root RadMenuItem1">
                            <telerik:RadMenuItem runat="server" Text="Child RadMenuItem 1">
                            <telerik:RadMenuItem runat="server" Text="Child RadMenuItem 2">
                            <telerik:RadMenuItem runat="server" Text="Child RadMenuItem 3">
                    <telerik:RadMenuItem runat="server" Text="Root RadMenuItem2">
                            <telerik:RadMenuItem runat="server" Text="Child RadMenuItem 1">
        <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
        <asp:Button ID="Button1" runat="server" Text="Button" />
    And now when I open that page Firefox, everything is ok. In IE8 there is an error - child items in menu are white. I attached screens:

    How to fix this?
  2. Answer
    Kamen Bundev
    Kamen Bundev avatar
    1532 posts

    Posted 07 Sep 2010 Link to this post

    Hello Jaromin,

    Unfortunately this stems from a bug in Internet Explorer (all versions). Since opacity CSS3 property is not implemented up to and including IE8, jQuery uses filter: alpha() to make the element transparent. The bug in IE is that stacked filters that contain an element with position: relative produce very weird results like missing text or sometimes even fully transparent element that can drill down even through an iframe. I would advise against using filters at all or at least on elements that don't stack (instead of applying the filter on the whole page you can apply it on a div above the content) but if there's no other way - you can just disable the overlay in RadMenu (which takes care of overlaying select elements in IE6 and Flash objects in all IE browsers and is basically a hidden with filter: alpha() iframe) and the issue will most likely go away.

    All the best,
    Kamen Bundev
    the Telerik team
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