Masked element still affects the height?

Hi all,
im trying to make this:

i have a movieclip, and inside it, there is a movieclip what have been masked.
The thing i just found out (by the hard way) that even the masked elements do affect to the movieclup heigth where the elements are.

and i even found out that the mask itself dows grows the _height value of the parent movieclip.

Is there a any way to go around this?
i would like to make it so that only the elements what are visible affect the _heigth value.

thanks