currently, the lookup strategy is hard-coded in getString(...) to query the UIManager for a localized value. In different contexts, there might be other strategies - f.i. query a resource managed by an ApplicationContext (in BSAF).
A way to support those differing contexts is to extract the actual lookup (after building the key) and let it default to looking into the UIManager. Subclasses can override to implement looking whereever they want to.