After the official release of KDE 4 last year, I took a close look at nascent projects that aimed to port the desktop environment to other operating systems. These ports have matured significantly over the past twelve months and are beginning to approach the point where they are robust enough for general use.

The open source KDE desktop environment, which is one of the two most popular Linux desktop stacks, underwent a significant transformation during the transition to version 4. Many parts of the environment were written from scratch and large parts of the underlying development infrastructure were overhauled. One of the major changes that accompanied this transition was the adoption of Qt 4, the next major version of KDE's underlying toolkit. Qt licensing changes that coincided with the launch of Qt 4 made it possible for the KDE developers to port the desktop to Windows and Mac OS X. The porting effort was also greatly simplified by KDE's adoption of the CMake build system.

With the KDE 4.2 release right around the corner, it's time to take another look at the KDE porting effort and see how the popular desktop environment performs on Windows. We installed the KDE 4.2 release candidate on Windows XP and tested a wide range of KDE applications.

Installation

The KDE on Windows team provides a wizard-based Windows installer that automatically downloads and installs the desired components. The user can choose which parts of the KDE stack are included in the installation by selecting application categories or by selecting specific packages. The installer lets users choose from several different versions, including the latest stable release and the latest development release. The application category list also allows users to install additional localization bundles so that the software can be used in their native language.

I included most of the application groups in my test installation, which added up to about 650MB of disk space. The complete install consists of numerous utilities, graphics editing software, development tools, multimedia programs, and the complete KOffice suite. It's an extremely expansive assortment of programs that cover a broad variety of tasks.

The installer sets up launchers for the applications on the system Start menu. It does not, however, add an uninstaller entry to the Windows "Add or Remove Programs" list. The KDE installation is pretty much self-contained, so it can still be uninstalled by deleting the directory in which it was installed, which defaults to C:Program FilesKDE.

Visual style and native platform integration

The Qt toolkit has support for using native widget styles on Windows and other platforms. KDE on Windows automatically uses the native theming engine by default in order to increase visual integration with the rest of the Windows environment. This works pretty well for simple applications, but some of the more sophisticated widgets look a bit awkward and out of place. It's sort of an uncanny valley effect.

Fortunately, you can configure the environment to use a different theme engine. I generally felt most comfortable using KDE's own Oxygen widget style. The KDE configuration tool does not appear to be included in the Windows installation, so you have to manually edit the configuration file by hand. Documentation that explains how to configure the style and other aspects of the environment are provided in the KDE on Windows installation instructions at the project's wiki. You can also configure KDE applications to use the KDE file dialogs instead of native Windows file dialogs.

KDE on Windows with the Oxygen theme