Flex Migration Pitfalls - apache/royale-asjs GitHub Wiki

Royale emulation components are based on a Royale version of UIComponent which is derived from UIBase. UIBase has some methods and properties, such as 'model', 'view', 'element', which do not exist in Flex UIComponent. If your legacy code extends UIComponents to use these APIs, the Royale compiler may not detect the override properly, but you will encounter runtime errors further on.