I am building a complete site using OOP AS2. I want to be able to change the size of the flash window (the stage) according to the "page" that the script is currently showing. In other words, different pages will have different hieghts and I will need the browser scrollbar to act accordingly.
Must javascript be used?
No, not at all, it's just that things were done differently.
You are looking for:
_root._height;
To resize the lash SWF once it has been written to the browser HTML, yes you will have to use Javascript.
This technique is a bit old, but it should work for you. I'll also see if I can update it a bit and post a newer version.
If you really need to resize your flash content, I suggest you to take a look in the famous SWFFIT script http://swffit.millermedeiros.com/ it resizes the flash content using javascript, and take care of all the hard work on it, you'll just need to call some javascript functions, but the whole script is well documented and easy to use.