createTextField and autoSize

How would I go about doing the following:

I create a textfield with AS and have to give it a certain height and width, everything is fine so far.

However, I want the textfield to expand to contain all the text I load into it.
Problem is with the autoSize property. I want the left side of the textfield to be in a fixed position, also the textfield needs to have a fixed width, so only the bottom of the textfield should adapt.
But how?? If I use autoSize = true then it changes the width of the textfield instead of the height… :frowning:

Any thoughts?