i3lock is a popular X11 screen lock utility. As far as customization goes, it only allows one to set a background from a PNG file. This limitation is part of the design of i3lock: its primary goal is to keep the screen locked, something difficult enough with X11. Each additional feature would increase the attack surface and move away from this goal. Many are frustrated with these limitations and extend i3lock through simple wrapper scripts or by forking it.
The first solution is usually safe, but the second goes against the spirit of i3lock.
XSecureLock is a less-known alternative to i3lock. One of the most attractive features of this locker is to delegate the screen saver feature to another process. This process can be anything as long it can attach to an existing window provided by XSecureLock, which won’t pass any input to it. It will also put a black window below it to ensure the screen stays locked in case of a crash.
XSecureLock is shipped with a few screen savers, notably one using mpv to display photos or videos, like the Apple TV aerial videos. I have written my own saver using Python and GTK.
It shows a background image, a clock, and the current weather.
XSecureLock is an X11 screen lock utility designed with the primary goal of security.
Screen lock utilities are widespread. However, in the past they often had security issues regarding authentication bypass (a crashing screen locker would unlock the screen), information disclosure (notifications may appear on top of the screen saver), or sometimes even worse.
In XSecureLock, security is achieved using a modular design to avoid the usual pitfalls of screen locking utility design on X11. Details are available in the Security Design section.
I have been using the awesome window manager for 10 years. It is a tiling window manager, configurable and extendable with the Lua language. Using a general-purpose programming language to configure every aspect is a double-edged sword. Due to laziness and the apparent difficulty of adapting my configuration—about 3000 lines—to newer releases, I was stuck with the 3.4 version, whose last release is from 2013.
It was time for a rewrite. Instead, I have switched to the i3 window manager, lured by the possibility to migrate to Wayland and Sway later with minimal pain. Using an embedded interpreter for configuration is not as important to me as it was in the past: it brings both complexity and brittleness.