mrglockenspiel/activate-linux

This project takes the "Activate Windows" watermark that Windows displays in the bottom-right corner of the screen when the operating system is not activated, and puts it on Linux instead. It is a purely cosmetic joke program written in C. When you run it, a faint "Activate Linux" message appears in the corner of your desktop, mimicking the familiar Windows nag screen. The program is built using Cairo, a graphics drawing library, along with Pango for text rendering and a collection of X11 and Wayland libraries for interacting with the Linux desktop. These are all standard libraries available in most Linux distributions. On Wayland-based desktops the program uses Wayland protocols, and on older X11-based setups it uses the corresponding X11 libraries. There is also an optional configuration library that lets you tweak settings via a config file. Installing it on Linux is straightforward. Ubuntu users can add a community-maintained package repository and install it with standard apt commands. Arch Linux users can get it from the AUR, the community package index for that distribution. NixOS users can run it directly as a Nix flake without installing anything. Gentoo users have an ebuild available through a community overlay. Windows users can install it through the Scoop package manager. macOS support is described in the README as "horrific" and requires setting up an X server separately. Building from source requires running make on Linux or following a slightly longer set of steps on Windows using the MSYS2 environment. The project also supports Xmake as an alternative build system. The license is GPL v3, meaning the source code is freely available and any modifications must be shared under the same terms. This is a novelty project with no practical purpose beyond the joke. The README even opens with a humorous Portal 2 quote to set the tone.