SwingJS has a small number of fields and methods that are added to standard Java classes or in classes that are inserted into the Java hierarchy (java.awt.JSComponent.java superclass of Container, for example). It is possible for a developer's subclass to cause problems with overloading these fields and methods, because they will not be identified by the j2s transpiler in projects other than java2script itself. The fields, at least, were marked by a starting _. This caused a problem with Varna using _border, for example. So the _ has been replaced by Mandarin "secret", 秘 u+79D8.