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asp.netcssajaxcontroltoolkitmodalpopupextender

ModalPopupExtender doesn't work on IE6 frame layout

I'm using a "frame" layout similar to the one in this excellent answer: a div #top at the top of the page, a div#left on the left, and a div #main with the main content. The #top and #left divs contain navigation menus.

Now I want to use a popup div using the AjaxControlToolkit ModalPopupExtender inside the content (#main) div.

This works fine on IE8 (where #top, #left, #main all have position:fixed), but when I run it on IE6, the modal background only covers the #main div - I need it to cover the whole of the page including the #top and #left navigation divs.

Looking at the script for ModalPopupExtender, it appears to be searching up the parent hierarchy until it finds a parent with position relative or absolute. And in the IE6 rendering, the #main div has position:absolute because position:fixed is not supported, which I guess explains what is happening.

Any suggestions for the best/easiest way to get this working properly on IE6? Ideally without modifying the ModalPopupExtender code, but I'll do this if I have to and it's the best solution.

Solution

  • I've implemented a variant of the solution in this answer, which appears to solve the problem:

    • For IE6, conditionally make the #main div position:static with margin-left equal to the width of the #left div. Unfortunately margin-top doesn't seem to work in IE6, so...

    • For IE6, conditionally add an empty div with the id ie6-spacer before the main div.

    • Set the height of the ie6-spacer div to the same height as the #top div.

    This appears to the trick.

    <!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>
  <title>'Frames' using &lt;div&gt;s</title>
  <style type="text/css">
    * {
      margin: 0;
      padding: 0;
    }

    html, body {
      height: 100%;
      overflow: hidden;
    }

    #top, #left, #main {
      position: fixed;
      overflow: hidden;
    }

    #top {
      top: 0;
      width: 100%;
      background-color: #ddd;
      height: 100px;
    }

    #left {
      left: 0;
      top: 100px;  /* move everything below #top */
      bottom: 0;
      background-color: #bbb;
      width: 120px;
    }

    #main {
      top: 100px;
      left: 120px;
      bottom: 0;
      right: 0;
      overflow: auto;
    }
  </style>
  <!--[if IE 6]>
  <style>
    #top, #left {
      position: absolute;
    }

    #ie6-spacer {
        height:100px;
    }

    #left {
      height: expression((m=document.documentElement.clientHeight-100)+'px');
    }

    #main {
      margin-left:120px;
      height: expression((m=document.documentElement.clientHeight-100)+'px');
      width: expression((m=document.documentElement.clientWidth-120)+'px');
    }
  </style>
  <![endif]-->
</head>
<body>
  <div id="top">Title<br /></div>
  <div id="left">LeftNav<br /></div>
  <!--[if IE 6]>
  <div id="ie6-spacer"></div>
  <![endif]--> 
  <div id="main">
    <p>
        Lorem ipsum ...<br />
        <!-- just copy above line many times -->
    </p>
  </div>
</body>
</html>