In our roadmap we stated that for 0.2 we were going to improve the conversation window, and especially make it customizable. Let’s show you an overview of what we did.
Smileys
People are used to see little images like 
in conversations instead
of the plain text version :-). Testers of Instantbird 0.1.* have
probably noticed that this feature was missing. No more.
Instantbird 0.2 supports smileys, and has a theme system for them. Creating a new smiley theme is easy: it is just a bunch of images and a file (JSON format) describing how to use them, bundled into an XPI file.
Message styles
Selecting a smiley theme is not enough for you to feel comfortable when looking at your conversations? Ok, we have more! We have borrowed the message style system of Adium to let you fully customize the way your conversations look.
An image is worth a thousand words so… I’m gonna give you a thousand of images. Ok, not really a thousand, but we took a few hundreds of screenshots to show how Instantbird is doing with the hundreds of Adium message styles downloadable from adiumxtra.com.
The compatibility is not perfect because there are some differences in the way Instantbird and Adium handle themes, and some Adium themes may use some webkit-specific features, but most themes look right.
This theme system is very flexible, and quite easy to learn. The technologies used (HTML, CSS, JavaScript) are well known by web-developers and web-designers. If you are not happy with the existing themes, go ahead an create your own. And don’t hesitate to let your creativity play with all the cool new developer features of Firefox 3.5.
Extensibility
The eye candy is cool but… I’m a developer, I want to create extensions and I want to be able to interact with the conversations! Don’t worry, we love you too. We added several new APIs for extension developers. It is now easy, for example, to change the way we filter incoming messages, modify the text before it is displayed (adding links for instance), and more coming!
Glad to see you’re not supporting custom Template.html files; that’s been a thorn in our side for years.
Could you please tell me how canI install an Adium message style in Instantbird? Firefox doesn’t recognize the file so it won’t download it nor will other downloading program.
@(anonymous): there are some packaging differences so even if Instantbird uses the same themes as Adium, the file is a little different (it needs to be a valid .xpi file for Instantbird). You will be able to download message themes from addons.instantbird.org once this site is ready (very soon!).