I just answered this on Stack Overflow, so I thought I’d share: when you use a rich text editor in a web page, such as nicEdit, if you type a URL or an email address into the text box in IE, it’ll automatically turn it into a link. On Firefox, it doesn’t. So what’s the deal, and can you turn it off?
tl;dr: It’s a Microsoft design decision, but as of IE9 you can disable it through javascript.
Here’s the setup: Windows-based browsers instantiate a MSHTML rich text editor to do their rich text stuff. There’s a setting in there, called IDM_AUTOURLDETECT_MODE that determines if URL auto-linking is on or off. It’s an ActiveX control, so if you’re putting it into a desktop app, you can use IOleCommandTarget::Exec and set it to whatever you want. If you’re building a web page, however, you’re out of luck, or at least you used to be.
There are some settings that you can tweak through Javascript, but until recently this wasn’t one of them. The document.execCommand takes a string parameter to specify the command you’re accessing, but there wasn’t a mapping in the back end to turn that into a value that the editor knew what to do with.
As of IE9, Microsoft has enabled a mapping for this called AutoUrlDetect, so now, if you’re lucky enough to have an IE user visit with IE9, you can call document.execCommand(“AutoUrlDetect”, false, false) and autolinking will be disabled.
For other versions of IE, life continues to suck. There aren’t any really good ways I can see to get around this without nuking all links in the text box, some of which might have been legitimately placed there.
In the grand scheme of things, it’s a minor annoyance, but one that I’m glad there’s a fix for as well as documentation around. There’s always something that a client will notice happening in one browser and not others, and for whatever reason this might be flagged as a show stopper in your project, because of course you can do anything if you put your mind to it, right? At least now the problem is known and is on the (slow) way out, and Microsoft has info on the original problem and the fix in case my word isn’t good enough 
Oh, and in case you want to go the other way: if you try the opposite of that code in Firefox on a machine with IE9 installed (so document.execCommand(“AutoUrlDetect”, false, true);), it doesn’t seem to work, which is probably just as well, since I’ve no idea what the equivalent would be on non-Windows machines. All in all, this seems like the kind of thing that javascript should control.
