Auto alignment of floating menu

[essayer2]

I have adapted Roy Whittle's script for a floating menubar, with a mod for having it spread horizontally. Within the script one can adjust the relative X and Y imaginary axis to which the menubar will set to. This feature is fine if everyone were to be viewing things through a rigid framed browser. But how about if the browser's frame size is infinitely changing, then how would one make the menu bar always align its horizontal center, with an imaginary centrally placed, vertical running axis within the browser window?

Any quick solutions to the code?

[ddadmin]

Warning: Please include a link to the DD script in question in your post. See this thread for the proper posting format when asking a question.