hierMenus.js

I am working with the the open-source Hierarchical Menus script on a web 
page.  It appears to have two options for positioning.  The default is 
where the mouseover event occurs.  The second is to absolutely position 
the x and y coordinates.  For example below, I'm setting a menu that's 168 
px wide and will be vertically placed at 71 px.  The x coordinate will 
dynamically be set on the <a href="#"><img></a> set of tags.

arMenu4 = new Array(
168,
"","71",
"black","white",
"#F84130","#FF5F4E",
"#9A0E20","white",
"Experts","http://www.webreference.com/experts/",0,
"Services","http://www.webreference.com/index2.html",1
)

MY QUESTION: Has anyone attempted to read the horizontal width of the 
browser window and then set the x value?

MY PROBLEM: I have a table that expands to 90% width and my rollover 
images are in a <TD> that is align="right".  So I can't absolutely set the 
x value in the array.  I can leave the x value blank, but I would like the 
pulldown to appear consistently irregardless of where the user mouseovers 
on the rollover.

Thanks!