> However (considering the bug fixed for the collapsed thread display), breaking the thread is not a confortable solution. 

Well, but it's the only way which gives you a 1:1 correlation between what you filter and what you see below. If you want to 
see the full thread for an entry which gets shown after you apply a filter, just click on that entry, and you will be taken to 
the single entry display which shows the full thread on top of it. This is the only way I can keep search results consistent, 
so I would rather like to keep it like this.