Upgrading to a major new version of Firefox is carried out with a certain amount of trepidation. After years of using Firefox I have it ‘how I like it’, and that includes my favourite theme Camifox. And here’s the first piece of bad news… Camifox is not being updated for Firefox 4. That’s a shame.

An upgrade is very likely to expose some non-supported plug-ins, and it’s likely to give Mrs A a case of the wobbles – as Firefox is installed on the family iMac, an upgrade for me is an upgrade for everyone.

But ignoring these minor disasters, here’s a quick run-down of some of the more prominent new features:

  • Tab groups – I usually have loads of tabs open, often because I want to read something later or have something open that prompts me to do something on my to-do list. I have a number of things I always need to have open (Facebook, Twitter, Connections Profiles), but the other stuff doesn’t always need to be visible. So the ability to group tabs together, hide a set but have the ability to return to the tabs is extremely useful.
  • App tabs – having established that there’s pages I always want access to, wouldn’t it be great if they could be pinned onto the tab bar with no close button? Yes… and that’s what app tabs are for. Nice.
  • More screen real-estate – the new layout of Firefox 4 provides a bit more vertical space… not a lot, but any reclaimed real-estate is a good thing.
  • Tabs on top – as the name of the feature suggests, the tabs are moved to the top. This provides even more reclaimed real-estate… but it may take a bit of getting used to.
  • Switching to tabs from the ‘awesome bar’ – if you type in the name of an open tab, Firefox shows that it’s a tab rather than an address in your history, and gives you an option to switch to it.

The following screenshot shows the new menu button (available on Windows and Linux, the Mac version retains the standard OS X menu), tabs on top, and three app tabs. Note that Twitter glows blue because the page has updated in the background.

Firefox 4 is rumoured to be faster than it’s predecessors – I haven’t witnessed any noticeable difference yet. All-in-all it’s a worthy upgrade, even without my beloved Camifox.