Dynamic textbox to auto extend

i have a dynamic textbox that loads text data from an external xml source. however, i won’t know how long the data in the xml is going to be. it could be a few sentences or a few paragraphs.
but this dynamic textbox that i have will only stay at the height i have set when working in flash.
so sometimes when the data from the xml has quite a few paragraphs, some of the text are not shown in the textbox because its height is not long enough.
is there a way to make the textbox to extend its height itself automatically on runtime?
thanks :}