Been looking over creating custom themes, through the main source as well as your demo theme project. Question: If I want to set multiple custom themes in different parts of my application, is it as simple as setting the root object in Theme.setTheme(MyFirstTheme, rootDisplayObjectToTheme), and its children will inherit that theme? And setting a second theme to another root object to do the same? Just want to verify if that's how it's designed to work.
Yes, that's exactly right. When a component is added to the display list, it basically walks up the parent chain until it finds a theme. So, when you set the root of a theme, all children are included, and any themes further up the chain will be ignored.