Non-fiction: XScreenSaver

Overview
Jamie Zawinski’s XScreenSaver, begun in 1992, is both a piece of software and an ongoing body of documentation that explains how screensavers, screen locking, and X11 graphics actually work. As a non-fiction project, it reads as a practical treatise on display technology, Unix portability, and user security, doubling as a chronicle of desktop computing from the era of CRTs to modern power-managed displays. The work’s throughline is simple: a screensaver should reliably blank the screen, lock it securely, and, if desired, display visualizations, without compromising stability or portability.

Origins and context
The project emerges from early X11 workstations where burn-in was a real concern, vendor behavior was inconsistent, and there was no universal mechanism to manage idleness and locking. Zawinski frames the problem as one of standardization and trust: users need a single, predictable daemon that owns the idle timer and security boundary, rather than a scatter of ad hoc hacks bundled by vendors or desktops. From that starting point, XScreenSaver defines a baseline for how a screensaver should behave and how it should interact with the X server, power management, and input devices.

Design and architecture
The core design separates the “driver” from the “hacks.” The driver (the xscreensaver daemon) monitors activity, negotiates with the X server, blanks the display, and manages locking. Visual effects are external programs launched under the daemon’s supervision. This modularity keeps the core robust: if a visualizer crashes or misbehaves, the daemon continues to enforce blanking and lock policy. Configuration is centralized, with a control tool to start, stop, and test the saver, and a GUI to browse, preview, and tune the installed hacks. Settings are stored in standard X mechanisms so they can be managed system-wide or per-user.

Security is treated as non-negotiable. The daemon owns the keyboard and mouse when the session is locked and defends against focus-stealing or spoofing. Authentication is delegated to the system’s facilities, allowing site policy to dictate passwords and timeouts. Crucially, XScreenSaver keeps locking and display power management distinct: power-saving features like DPMS can turn the panel off, but the lock state must remain under the daemon’s control so that a wake event never reveals the desktop without credentials.

Principles and arguments
The documentation insists that “screensavers” do not save energy, turning the screen off does. Animations exist for aesthetics and delight, not conservation. That clarity shapes every choice: blanking is the baseline; visuals are optional; the lock is paramount. Zawinski argues for conservative interfaces and strict separation of concerns, critiquing desktop environments that intertwine compositors, lockers, and savers in ways that produce race conditions or bypasses. Portability is treated as a discipline: stick to widely available X11 and OpenGL features, ship self-contained hacks, and avoid coupling that would tie behavior to a single window manager or toolkit.

Culture and contributions
Over time XScreenSaver becomes a curatorial platform for visual experiments, dozens of small graphics programs, from simple geometric motion to OpenGL extravaganzas, each packaged as a first-class citizen but constrained by the driver’s rules. The essays and manual pages accompanying the software are as central as the code, explaining timing, input grabs, colormap issues, GL context handling, DPMS quirks, and the difference between reliable locking and window-dressing.

Legacy
As a non-fiction account of a living system, XScreenSaver documents three decades of lessons about user trust, security boundaries, and the realities of X11. It helped define the expectations for how a saver and locker should behave on Unix, and it influenced a generation of open-source visual “hacks” by showing how to be playful without sacrificing correctness. The project’s longevity underscores its thesis: simple, well-defined responsibilities, enforced rigorously, outlast fads and vendor reinventions.