title: Detail lifespan of all ActionScript3 object
body: <p>I use ActionScript3 to develop web and mobile game. Memory is my biggest enemy, I always don't know detail lifespan of some objects.
  For instance:
  Bitmap
  I know there is a "dispose" function of bitmapData. So always, I dispose a bitmap object by using "bitmap.bitmapData.dispose". However, I wonder if the reference of a bitmap object becomes 0, will GC free the memory used by this object even if I don't call dispose function.</p>
  
  <p>I have too many questions like above (Sound, Texture, BaseTexture...). Does anyone has some ideas about this topic?</p>