Why do Tab buttons resize temporarily?

Have you ever noticed that when you close a tab in IE using the tab’s red-X button (or middle-click): …the tab to the left gets wider (or narrower)? If you then move your mouse, then the tab button size goes back to normal: This is probably the most commonly reported “bug” that’s not a bug in the IE UI….


A Quick Look at P3P

Internet Explorer supports a cookie-restricting privacy feature called P3P. Web developers often get tripped up by it because no other browser implements the P3P standard. I’ve written about IE’s cookie control features previously (and more comprehensively), but here’s a summary of the “least you need to know.” P3P Made Simple By default, IE will reject cookies…


Same Origin Policy Part 2: Limited Write

In Part 1 of this series, I described how Same Origin Policy prevents web content delivered from one origin from reading content from another origin. (If you haven’t read that post yet, please do start there.) In today’s post, we’ll look at what restrictions are placed on writing between origins. What is a “Write”? For…


Detecting Captive Network Portals

Over on SuperUser, there’s a great explanation of how Windows determines whether a newly-connected network has a proper Internet connection, or whether the user should open a browser to login or click through a Terms of Use agreement. The general idea is that Windows will attempt to download a webpage from a well-known URL, and…


Internet Explorer 9 Help Files Online

In Internet Explorer, if you press F1 or use the Help menu, the Windows Help and Support screen will show. However, you may find that you always see a Topic not found error message. The reason is that Internet Explorer 9’s help files are available only online. To see the help content, click the menu…


YouTube and Save Video As

An amusing April Fool’s satire I ran across yesterday reminded me of a Connect bug that was reported back in the IE9 Beta. The HTML <video> control’s default context menu includes a “Save Video As…” menu option that allows saving the video to disk: The user complained that, when browsing YouTube with HTML5 Video enabled,…

What is msimgsiz.dat?

Inside your Temporary Internet Files folder you likely have a file named msimgsiz.dat. If you open this file, you’ll find that it contains nothing but binary goo: Over the years, many people have asked or speculated about what this file is used for, and the answer is actually quite simple. This file, used by MSHTML,…


Understanding the IE9 Software Rendering Mode

I recently heard from some users who are seeing lower-than-expected scores on the Speed Reading and FishIE Tank benchmarks. I went to check these tests myself and found that my laptop’s score was low. In fact, it was much lower than I’d seen last year. What happened? First, a bit of background: These graphically rich…


How to Uninstall Internet Explorer 9 Beta

If you want to remove Internet Explorer 9 beta from your computer and go back to your older version of IE, you can do so by simply following these steps.


Same Origin Policy Part 1: No Peeking

Despite its role as the cornerstone of web application security, it’s clear that many (most?) web professionals do not understand Same Origin Policy (SOP), or hold one or more misconceptions about what SOP requires. It’s a big topic, and I don’t plan to address it all on this quiet Friday morning. This post will be…