On GNOME the title bar row drew a thin stroked X on a 22 px disc of the
app text colour over sctk-adwaita's GTK 3 header grey. It now draws
libadwaita's window controls: 34 px buttons 3 px apart, a 24 px disc (20 px
before 1.8) at 10/15/30 % of the header bar ink at rest, hovered and
pressed, Adwaita's window-*-symbolic glyphs, the whole set at half opacity
in the background, over libadwaita's header colours. The libadwaita release
follows the running GNOME Shell (1.N with GNOME 41+N).

The buttons sit at the start or end of the row as button-layout places
them, re-read when the settings portal reports a change. Desktops other
than GNOME that leave decorations to the client get the toolbar's own
buttons rather than an imitation of Adwaita.

Assisted-by: claude-opus-5.5