Why this exists

The ring, Settings, Apps, Screenshot, Activity, Drives, the login screen, the lock screen and the Trindle Installer are all the same Rust binary. Nearly every trindle- command is a symbolic link to it, and the program picks its tool by the name it was started as. trindle --names lists them. The spots in the top corners that a finger taps to open the ring, and the box that asks for your password, go a step further and run inside the ring itself, rather than as two programs of their own, each with its own copy of the toolkit.

The compositor, which puts every window on the screen, is Trindle’s own too. It is called trindle-compose, it is written in Rust on Smithay, and it is kept as a program of its own, so the rest of Trindle never loads what drawing the screen directly needs. It runs the login screen as well as the desktop. For programs that ask the desktop to draw their title bar, it draws the title bar itself, with three buttons at the right: a line to put the window away, a square to fill the screen and a cross to close it.

That is not a clever trick for its own sake. It means one set of colours, one stylesheet, one place a bug gets fixed, and one thing to keep up to date. A new Settings page is one file in a folder plus one line in that folder's list.

Only trindle-admin runs as root, through pkexec. It checks every argument it is given and reads passwords from standard input only, so the rest of the desktop never needs to be trusted with them.