How to change an element size with animation?

Hi,
Would it be possible to change the size of an element with an animation?
I would like to expand a container containing some text with an animation.
Unfortunately, it seems the “height” and “width” are not part of the animation attributes object.
Then, I just tried to add another element, attached at the bottom of my container and to change its y coordinate thanks to an animation.
This works, i.e. at least the vertical translation of the element is animated, but the parent container is not resized accordingly: I would expect the parent container height to increase as the child element is translated vertically since the parent height is set as “auto”.
But it is like the child element is detached from the parent container and then translated.
I would avoid using the expand() method which does not allow any animation.
Does anyone know any technic to animate the height or width properties?
Thanks in advance