find.keyboardPopup() (finders.js VERSION 3) replaces the same
g_PopupManager lookup in the swipe, extra keys and touch typing patches
(VERSIONs 29, 24, 4). hub.js keeps its own: it gets no finder library.
Steam sends Tab as the text "\t" and drops Shift. With Shift, Tab now
goes to the xdotool helper (shift+Tab, ISO_Left_Tab on any keymap); the
suggestions text model resets on it like on Shift+arrows. The helper's
allowlist moves to allowlist.mjs with a test (flake check
vr-keyboard-extra-keys).