Hello,
   I gave it a try using the svn version n. 2283 (12 Jan 2010).  The threaded display can be collapsed only if you don't 
apply any sorting. In the latter case, if you sort in some way ( with "Sort Attributes =" or "sort=" in the url), the 
thread cannot be collapsed anymore.

Also if I apply any filter from the quick filter bar, I cannot collapse the thread anymore (also without sorting). 

As example, these are the numbers of entries I obtain with my logbook :

  http://localhost:8080/mylogbook/?mode=threaded&expand=0     => 75 entries (OK)
  http://localhost:8080/mylogbook/?mode=threaded&expand=0&sort=EventID  =>  445 entries  (WRONG it should collapsed)
  http://localhost:8080/mylogbook/?mode=threaded&expand=0&Interaction=nuCC   => 335 entries 

However (considering the bug fixed for the collapsed thread display), breaking the thread is not a confortable solution. 
I choose to show the logbook in the threaded mode, because I'm interested in grouping the entries in threads. 
In my opinion, this feature is good (and it is my favourite) and should be preserved despite any sorting or filtering. 
This is why I suggest to ask to the user which entries (first or last) better applies for sorting and filtering. 

Ciao

   Gabriele


> You are absolutely right. When doing filtering, entries shown or not shown have not much to do with the filter. 
> Rather than messing around with first and last entries, I decided to break apart threads completely when doing 
> filtering, so the entries are treated as individual entries, just like what you do when filtering in summary mode. 
> This gives then consistent filtering results. The modification is done in revision 2282.