dvKioskAllowsExternalUrl function
Whether a running kiosk policy permits opening url outside the
application, per routes.external.
True when no kiosk holds, so an ordinary build is unaffected and a link
in staff mode opens the way it always did. A relative path is a route
rather than a way out, and this says yes to one: routes.allow is the
key that governs where the application may navigate itself.
Implementation
bool dvKioskAllowsExternalUrl(String url) =>
_holding?.allowsExternal(url) ?? true;