The Lightweight X11 Desktop Environment (LXDE) [1] is a flyweight among the desktop environments. Needing a minimum of just 45MB of memory, the LXDE desktop is light enough to run on low-powered notebooks or older computers with only 128MB RAM and a Pentium II CPU (Figure 1).

Figure 1: The lightweight LXDE desktop can run on antique hardware.

The ultra-lightweight LXDE has built a loyal following in the Linux community for its ability to conserve resources and run on old hardware. LXDE is actually the default desktop for Knoppix, and the LXDE-based Ubuntu variant Lubuntu typically outperforms other alternative Ubuntus at the DistroWatch site [2]. The LXDE desktop first found its way into the Mandriva and Fedora repositories by 2006, and later it became available for Debian and openSUSE. Android and the free router firmware OpenWrt also support LXDE. Many other distributions offer packages or installation images with LXDE, and you'll even find versions of LXDE for OpenSolaris [3] and various BSD systems [4]. The individual LXDE modules are all suitable for independent operation in other POSIX-compliant [5] environments, and the LXDE desktop observes all the rules [6] created by the Free Desktop Project and defined as the Linux Standard Base (LSB) [7].

You might say that LXDE has been on a roll in recent years, winning converts all over the world, but the project recently faced a crisis. The LXDE desktop is based on the Gtk+ version 2 toolkit [8], the same toolkit used with Gnome. Gtk+ provides widgets and other programming tools used to build the visual elements of the desktop. The Gtk+ version 3 toolkit was released in 2011, and many desktop developers have been porting their code to Gtk+ v3 in preparation for the inevitable end of support for Gtk+ v2. Chief LXDE developer Hong Jen Yee (also known in the FOSS world as PCMan), explored the possibility of upgrading to the new version but ultimately decided Gtk+ v3, which is not backward-compatible with its predecessor, made less frugal use of resources and would require too much programming effort.

Yee decided to stay with Gtk+ v2, and because he knew that support would end at some point, he began work on a new variant of LXDE based on the alternative Qt toolkit [9], which is the basis for the KDE desktop. This work led to a spinoff project known as LXDE-Qt or LXQt. Ultimately, the team decided it would be less trouble (and produce a better outcome) to ship the main development effort to the Qt branch rather than to upgrade LXDE from Gtk+ v2 to v3. For now, the Gtk+ and Qt versions of LXDE are supported in parallel, but when the Gtk+ project ends it support for Gtk+ v2, the LXDE team will end its support for the Gtk+ version.

New Friend

FOSS projects originate from good ideas, which often occur to more than one team of developers. The LXDE project wasn't the only community working on a lean and light Free desktop based on Qt.

The Razor-qt desktop environment (Figure  2), initiated by Russian developers, is another lightweight system built on Qt. Razor-qt comes with a panel, a desktop, an application launcher, and tools for configuring and managing sessions – plus it supports a wide range of window managers, including Window Maker, fvwm2, IceWM, Compiz, and i3.

Figure 2: Razor-qt, which is also based on Qt, does without unnecessary ballast and is thus fine on slow computers.

Razor-qt development had stagnated for some time because of a lack of developer capacity. Hong Jen Yee posted an announcement on the Razor-qt developer list in March 2013 and released his PCManFM file manager [10] in a version he had ported to Qt 4. The makers of Razor-qt expressed their excitement, and Yee reported that porting the file manager to Qt had brought him closer to the framework. He could imagine, he said, joining with Razor-Qt, because both projects pursued the same goals.

Under One Roof

At the 2013 KDE Akademy conference in Bilbao, developers from the LXDE-Qt and Razor-qt desktop environments met and decided officially to join forces [11]. Since then, both sides have been working on the shared environment LXQt. The project aims to combine the best components of both worlds. Another result of the Academy 2013 conference was the offer by KDE to put the new project under the auspices of KDE, so LXQt can leverage the existing KDE infrastructure.

The makers of the Siduction distribution have created an ISO image of their system with the LXQt desktop. The image, which is a development release, is only available as a 64-bit version and is not designed for production use; however, it offers an easy way to experience the LXQt desktop. The Siduction ISO [12] has a clean upgrade path and will show a more advanced development stage of LXQt after performing a dist-upgrade.

The modules used for the LXQt ISO are based on Qt 4 – the LXQt developers are skipping the current 5.0 version. At the moment, they are preparing and building the individual modules for Qt 5.1. Among other things, the file manager PCManFM is already available in an early version for Qt 5.1 and comes with rudimentary compatibility with the Wayland display server protocol [13]. The current versions of the applications on a Qt 5.1 basis are not yet optimized, and they are also fairly unstable.

In the ISO, Qt applications such as the lightning-fast QupZilla browser, the Amarok descendant Clementine, the JuffEd text editor, QTerminal, qBittorrent, or Qlipper complement the desktop (Figure 3). Siduction will add LXQt to its release cycle during the year as soon as a stable version is available.

Figure 3: Although still in an early phase, the LXQt desktop already includes a large collection of tools – including the lean QupZilla browser.

Conclusions

LXQt currently requires slightly more memory than the Gtk+  v2-based LXDE, but the alternative Gtk+ v3 toolkit would also have required more memory. After launching, the Siduction image occupies just over 300MB of RAM; it is thus just about manageable for computers with 512MB of RAM. The login manager is SDDM: this QML-based digital gatekeeper is scheduled to replace KDM, which is no longer under development in KDE Frameworks 5.

The happy conclusion of the merger between LXDE and Razor-qt is a new direction and a robust, invigorated development team. We'll wait to see how the two virtual communities handle the problems of everyday life together.