v0.64.0 — GTK input routing
The GTK4-hosted Linux backend now routes pointer and key input to the Surface: clicks, scrolls and keystrokes reach the drawn regions (native controls still get theirs from GTK first). So the reader is fully navigable on Linux — proven end-to-end under Xvfb (a click on Settings opens the Settings view). Needs go-gtk/gtk4 v0.3.0.