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Is there a plugin, that lets you switch firefox browser mode, the way you can do in IE?

I want to see how my CSS renders in older ff versions. (To be exact, I want to see, how it renders on ff for Mac, but I do not think this is possible to emulate. So I want to see, if the error appears on older ff versions, too)

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closed as off-topic by Tog, random Jul 25 '13 at 16:26



like IE does? I'm not aware of IE allowing you to switch between different versions of IE. It has a compatibility mode, so you can switch between quirky and standards compliant rendering. Firefox has only one rendering mode: correctly. –  ta.speot.is Jul 25 '13 at 9:57
As far as I know, there isn't anything like that. Try using the portable firefox builds. –  Vanadis Jul 25 '13 at 10:27
@ta.speot.is: I would assume he's referring to being able to switch the "browser mode" in the IE developer tools. –  Oliver Salzburg Jul 25 '13 at 10:56
Yes, I was talking about the browser mode. And if firefox has only one rendering mode:correctly: How come that the website I'm working on displays different in FF for Windows and FF for Mac? I understand that my question does not meet the standards here, but you answer isn't very useful either. –  Lord_Mord Jul 25 '13 at 16:18

1 Answer 1

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What IE does when switching the browser mode is changing the user agent string (and possibly using some older rendering approaches).

Switching the user agent string in Firefox can be done with the User Agent Switcher extension.

After installing it, import a list of user agents from this forum post. You'll then be able to switch the user agents from the menu.

enter image description here

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Has this an effect on how CSS is displayed, or depends that only on rendering? How can I switch the rendering mode? –  Lord_Mord Jul 25 '13 at 16:14
@Lord_Mord: No, changing the user agent string doesn't affect CSS rendering. If you want older rendering engines, use portable versions or a virtual machine. Rendering differences between operating systems can have all kinds of other reasons though (starting with the availability of fonts). –  Oliver Salzburg Jul 25 '13 at 18:57
Thank you. No this is a padding thing. There was a bug on FF (Windows), I could fix it with setting the padding to 7.5px, I know that this is very hacky. And that totally broke the padding on Mac. Dont mind, I will experiment with some older ff or maybe I will have to find someone with a Mac. They aren't very hard to find these days. –  Lord_Mord Jul 26 '13 at 10:03
I'm fairly sure though, the user agent string doesn't affect the Javascript either, so for testing things like Jquery, this may not help :( Now, this answer is 'old' but, since it was answered in IE you can now change it via the document mode –  Dave May 22 at 11:33
