TextField's width changes automatically

Hi, I’m using the Tween class to change the _yscale properties of a created movie clip, which contains a created text field. (everything done in AS).

When I change the yscale value of this mc, the text’s width inside automatically decreases along with the height. This is not the effect I’m looking for.

After racking my brains for half an hour I realized that it makes sense that the text’s width decreases because since there is a dynamic text field inside the mc that Im scaling, when I scale it’s y parameter, the text insie would get smaller (I think?) So then I used the same tween to change the yscale of the textfield instead of the mc which holds it - but the same thing happens.

How can I scale the height of the mc that holds the textfield without scaling the width of the textfield inside it? :jailbreak