Flexible Gaming: Using Canvas Versus UIComponent?

For developing simple games with the Flex SDK, what are the implications of using a Canvas versus a UIComponent as a drawing surface? Are there any performance issues? Are the methods generally the same? Searching around, it seems that most of the code examples I have found use UIComponent. Is this common or is there a reason?

I already know one strange difference - I developed a simple Pong game using:

    public class MyGameCanvas extends UIComponent

      

        
        
        
      

    

and then decided to replace UIComponent with Canvas. This caused the line to fail:

addChild(paddle);

      

        
        
        
      

    

After spending too many hours searching, I finally found that the Canvas object requires:

rawChildren.addChild(paddle);

      

        
        
        
      

    

due to the chain of inheritance of objects, Sprites above Canvas.

But it doesn't seem like preferring one class over the other. Are there any specific reasons? Thank.

Update: Ok, I'm assuming Canvas is missing and UIComponent is enabled. The only reason I even tried the Canvas object is for the name. I mean this Canvas is not where you should be doing drawing? :)

So the second question that came up was about using the Flex SDK (and I don't know if this should be a completely new question, or if it's okay here).

However, I have to confirm something by being new to Flex and different terminology. I'm guessing people mean I shouldn't use MXML for games when they said Flex SDK. As I thought the Flex SDK was what the compiler provided that generates the .swf files. Otherwise, where / how could I compile AS3?

Assuming that is the case, then my question would be about the usability of both MXML and AS3 for (simple) games. Based on what I read about both, it seemed like their use was MXML for UI elements, and AS3 for everything else. Is the overhead bad for MXML?

John C>