The code works with Flex 3.5. If you look at the code, I added the TextField to the display list of managerContainer which is a UIComponent.
The problem with FlexTransformManager is actually that it extends a Canvas and not a UIComponent so that we can't directly add TextField. I know I could use TextInput or TextArea instead, but these Flex components are not easy to customize (font, size, color) when you add them dynamically with AS3 code.
Your Flex example is using "static" tags nested into FlexTransformManager. So how would you add new text items dynamically and customize it from the Flex version?
That's why I prefer using the AS3 version of TransformManager with a UIComponent. I tried to modify FlexTransformManager to use UIComponent instead of Canvas, but it still doesn't work
The real issue is TextField items are not displayed anymore when using Flex 4 and I have no idea why. I join my code again. Compile it with Flex 3.5 and Flex 4, you will see that the exact same code works with Flex 3.5 and not with Flex 4.