Emerald Overview

Although Compiz Fusion renders the actual windows and controls their behavior effects, you are still stuck with the original GNOME/KDE window decorations by default. However, there is a window decorator program called Emerald that allows you to use better-looking window decorations. Emerald was originally designed to work with Beryl, hence the naming trend; the gemstone emerald is technically a variety of Beryllium. Emerald has been around for awhile, but it still works as a drop-in replacement for the standard Window decorator in GNOME or KDE.

Emerald uses “theme” files to produce window decoration effects. These themes each use an engine that specializes in a different effect (e.g. TruGlass for transparency effects and Vrunner for gradients) Each theme is built around a specific engine; this is a factor to consider when constructing your theme since switching engines can produce vastly different effects.

If you want to use Emerald, you must install it manually. Fortunately, Ubuntu and many other distros have Emerald in their repositories; Ubuntu users need only type “sudo apt-get install emerald” to install Emerald. By default, Compiz Fusion will not use Emerald; you must manually invoke it through CCSM in the “window decorations” module. To do this, locate the “command” field in the window decoration module and replace the original value with “/usr/bin/emerald --replace”. The changes should take effect at the next login. You can invoke the changes immediately by opening a terminal and running “nohup emerald --replace” after re-configuring CCSM to use Emerald with the previous command.

To avoid problems, make sure you have at least one Emerald theme installed before you enable Emerald in Compiz Fusion. If you try to use Emerald without any themes, no window decorations will be rendered at all.

Creating Emerald Themes

If you just want to use other people's Emerald themes, there is an abundance of them at gnome-look.org. To install a theme, extract the .emerald theme file you wish to install from its tarball to a location in your home folder and click the “import” button in the Emerald program interface. Locate the file you extracted, select it, and then click “open” to install it. Emerald provides a list of installed themes; to switch to a theme, click on its entry in the main list.

The Emerald program also has a built-in interface for creating themes. Although the feature is called “Edit Theme” it can do far more than that. Once you understand how Emerald handles various graphics, it is possible to create new ones from scratch while using pre-existing ones as a reference. You do not need to include effects like drop shadows or glow in the image components of your theme, since Emerald is capable of generating such things dynamically.