If we serve the header:

X-UA-Compatible with the value: IE=edge

We can eliminate the "compatibility mode" / "make website ugly" button in IE9.





This will add 20 or so bytes to every request we serve to compensate for IEs "unique" behavior and protect users from clicking this button by mistake.

However, in the history of meta this has never been asked for so odds are this issue is totally "imagineered".

Should we bother serving this header?

  • can we presume that "every request" is not every single request but just pages? Commented Aug 24, 2011 at 2:11
  • +1 I hate those sort of buttons... Commented Aug 24, 2011 at 2:12
  • @davidsleep I guess ... that would be a slightly more complex change though
    – waffles
    Commented Aug 24, 2011 at 2:21
  • Was it just that you were going to add the header within IIS...or something that only adds the header to IE browsers (on all requests)? If the CDN is serving only static content at least all of that wouldn't need the header... Commented Aug 24, 2011 at 2:31
  • It's hard to judge the worth without seeing the effect Compatibility Mode has.
    – user154510
    Commented Aug 24, 2011 at 2:50
  • @Matthew ... it removes rounded corners everywhere (badges etc) it makes the "big fat search box" look really ugly, tag synonym page is ugly ... try it out ... edit welcome
    – waffles
    Commented Aug 24, 2011 at 2:54
  • 6
    I don't use IE so I don't really care about that button.
    – John
    Commented Aug 24, 2011 at 3:22
  • @John oddly enough I feel the same. Just wanted this out there and open for discussion.
    – waffles
    Commented Aug 24, 2011 at 4:38
  • 1
    It seems unlikely that many IE users press that button accidentally. It's a known feature of their browser, and if they choose to destroy the look of the webpage, well, that's their own fault. Just like if users on other browsers want to blow up their font sizes. (This is a great discussion though; thanks for sweating the details like this!) Commented Aug 24, 2011 at 16:45

1 Answer 1


Some data as of Nov 12, 2010:

for stackexchange.com and subdomains -- IE is 11.72% of all visitors.

for stackoverflow.com -- IE is 21.72% of all visitors.

I'd say at absolute most, maybe half of the IE users would be on IE9 and that's probably wildly optimistic.

So to summarize: we would be adding 20 bytes to every single page request, for ...

  • 6% of all visitors on Stack Exchange 2.0 sites
  • 10% of all visitors on Stack Overflow
  • whatever sub-percent of those users who actually care about this button and "accidentally" click it

Also, no user has ever mentioned this to my knowledge on meta, ever. So there's also no evidence this is an actual problem worthy of our time and 20 bytes on every single page request to all users, regardless of whether they use IE, and regardless of whether they know about this button.

Strongly opposed; data doesn't support it.

  • Totally unrelated and not questioning the data, but it seems a little odd to me that there would be a larger percentage of software developers using IE than "regular users" (Internet "power-users"?) visiting the other SE sites. Commented Aug 24, 2011 at 16:44
  • it didn't surprise me at all; it's a question of scale. SO is 100x larger than SU/SF and 1000x larger than almost all other SE 2.0 sites. Therefore its stats are more reflective of the general population, because the sample size is so much larger. Commented Aug 24, 2011 at 21:17
  • +1 Well, compatibly mode might also be useful for users that want to fix IE9-specific bugs. So just keep it... :) Commented Aug 28, 2011 at 1:32
  • for the record ... we could only add the header for user agent crappy ie.
    – waffles
    Commented Feb 2, 2012 at 0:39

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