I'm a bit confused by what seems to be a schizophrenic approach to properties and styles within the Flex 4 SDK. In some cases, components have properties that affect their visual appearance while in other cases they use styles. For example, here is a BorderContainer from an example in Adobe's Using Flex 4 docs:
<s:BorderContainer width="200" height="200"
borderColor, borderAlpha, cornerRadius and borderWeight are all styles. However, BorderContainer also has some properties for visual formatting; e.g.,: backgroundFill and borderStroke. The latter property equates to two of the styles: borderColor and borderWeight. But the former, backgroundFill, doesn't appear to have a corresponding style although there is a backgroundImage style.
So, I'm wondering why the SDK has this split personality. But more to the point, I'm wondering if there's some logical explanation. How do I know when to use a style rather than a property? Where should developers look first when seeking to modify the visual appearance of a control?