[Seaside] How to ensure a script appears only once on page?

[James Foster]

I'm looking at some of the YUI components, specifically the calendar  
widget, and am struggling with how to create a script. As I understand  
the YUI library, I am supposed to create a Javascript that references  
each of the calendar widgets on my page. The script has the general  
format of (begin, middle, end), where the middle has a variable amount  
of code but the begin and end are fixed. My problem is that I might  
have calendar widgets on various components, and the components should  
not each add the script, because then there would be multiple begins  
and ends.

Now, there might be a work-around for the YUI calendar situation, but  
I have a more general question: Is there some way to hook in to the  
beginning or end of a render process? I've come up with a crude  
approach where each component notifies the session at the beginning  
and end of a render and the session keeps track of the first in and  
then lets it know when it is the last out. Are there any other good  
ideas?

James