What does it mean when there's no "broken page" icon in IE8?

I was just catching up on some of my RSS feeds, and noticed that one of the pages I was at didn't have a broken page icon, but wasn't working quite right (some broken javascript in the photos area, I'm guessing... I'll investigate that next).

image

I wondered what that meant, so fired up Fiddler2 to have a look.

The Headers collection didn't include the compatibility header (X-UA-Compatible: IE=EmulateIE7 or similar):

HTTP/1.1 200 OK
Proxy-Connection: Keep-Alive
Connection: Keep-Alive
Content-Length: 77144
Via: 1.1 MYPROXY
Date: Wed, 10 Sep 2008 07:42:24 GMT
Content-Type: text/html; charset=utf-8
Server: Microsoft-IIS/6.0
X-AspNet-Version: 2.0.50727
Cache-Control: private

But the META tag was present (link):

<!doctype html public "-//w3c//dtd xhtml 1.0 transitional//en"
    "https://www.w3.org/tr/xhtml1/dtd/xhtml1-transitional.dtd">
<html xmlns="https://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
  <head><meta http-equiv="X-UA-Compatible" content="IE=7" /><title>
    Spied: New Mazda3

So: the page is being told to render in IE7 Standards Mode (forced, as opposed to IE=EmulateIE7, which would behave as IE7 did). This makes the toggle compatibility mode button moot, because the site has chosen their mode explicitly.

Wonder if that's the problem... Time to investigate with the developer toolbar, I think...

(Update: nup, document mode didn't fix it - Script Debugging needed to be un-disabled in IE, and then the debugger showed me it was happening in motiongallery.js. I've lost interest now :) )