Masking question

1

Can anyone point me in the right direction when it comes to “drawing” boxes? Is it simply a masking affect that gives the appearance that the box or object is being rendered? Here is a good example.

http://www.insite3.com/insite3_ui.htm - when you choose from one of their projects, see how the preloader box is shaped.

Thanks in advance.

2

it can be done either through sticking some shape tweens into a movieclip, or writing it out in AS.

3

does the file size increase a lot if done without actionscript