As part of the B2G (Boot 2 Gecko) or, as it's more commonly known, FirefoxOS project (Mozilla is creating an HTML5 operating system), they have created the pdf.js library.

pdf.js is an HTML5 technology experiment that explores building a faithful and efficient Portable Document Format (PDF) renderer without native code assistance.

pdf.js is community-driven and supported by Mozilla Labs. Our goal is to create a general-purpose, web standards-based platform for parsing and rendering PDFs, and eventually release a PDF reader extension powered by pdf.js. Integration with Firefox is a possibility if the experiment proves successful.

- https://mozillalabs.com/en-US/pdfjs/

So, you may have been wondering why PDF's viewed in Firefox are no longer using Adobe Acrobat reader, and, on occasion may not be faithfully recreating the artwork originally saved.

A quick check in (address bar) about:config will reveal a (boolean) pdfjs.disabled value. By default this is false.

If you want to revert to the more traditional Adobe Acrobat viewer then you can set this flag to true.

You can set the pdfjs.disabled pref to true on the about:config page to disable the build-in PDF viewer and use the Adobe Reader instead.

- https://support.mozilla.org/en-US/questions/950988

It also turns out there is support for this in other major browsers such as IE9+, Chrome/Chromium, and (albeit rather buggy) in Safari.

If you're having issues with PDF's not rendering correctly in the browser just have a quick look for pdf.js and maybe revert back to the native Adobe Acrobat PDF viewer.

Annoyed at various DNS restrictions I managed to find some articles out there on the t'internet on a nice little 'hack' that works in Firefox, sadly, only on the PC. Sorry Mac' guys....

Essentially all you need do is convert the IP address of your DNS name to HEX. Unless you were any good in math at high school this may take some pondering to calculate in your head so, some jolly nice people at kloth.net wrote a nice little lookup service.

To get the IP address for a domain name use a PING service. Once you have the IP address perform a HEX lookup using the kloth.net service and then use the following format in a Firefox URL bar. http://0x{HEX value}... and that's a zero right there. So for www.google.com the address would be DNS => IP = 72.14.205.100 => HEX = 480ecd64... so http://0x480ecd64/ is Google! est ! Voila... Remember this only works in FF on the PC.