Keep egui's keyboard focus in sync with our own focus flag for the surface `id`. While `focused`, the surface holds focus so `wants_keyboard_input()` stays true and egui consumes keystrokes (no OS default beep); when it loses focus we surrender it so other widgets behave normally.
(ui: &egui::Ui, id: egui::Id, focused: bool)
source not stored for this graph (policy: none)
no outgoing calls
no test coverage detected