[Zope] sort catalog results w/ table headers ?

[Nicolas LAURANCE]

hello,
here is my situation...
I would like the headers of the table containing the results of a 
catalog query, to be reversable sorting.
I'm not sure i'm clear, but just like in the FileLibrary example 
given w/ zope 2.5.
I studied this example and tried to modify it to suit my need but...
As it always starts a new query i get a new results sorted.
Say I have a result from the Catalog from a complex query... when I 
sort w/ the headers I loose my filter, all records comme back.
I don't know how to keep the parameters of the query (session ?)
As well, I need a default query to apply (the last 20 modified)
Everything works fine, but this.
I am not very familiar of the new TAL language... at the moment I 
still develop mostly in DTML & python scripts.
I think, I have a very standard situation, but found no info about 
that in my books, or the zope book, or the last 10,000 messages of 
this board.... 
any help appreciated