Deficient thread sorting in summary view

[F . Durand]

Hello all,

I've switched to gnus 3 months ago, and I'm very disturbed by the way 
threads are sorted.

I've read this many times: http://gnus.org/manual/gnus_91.html

I've concluded that the state of a thread is the state of its first message. 
Thus, if you have an old thread with a new message, you won't remark it.

Freshly harvested messages should be highlighted. Actually, they are 
highlighted, with a leading dot ("."). Except if the message belongs 
to a thread that is still displayed (because one of its messages has 
been pinned or is still unread). In such case, the thread will be 
displayed at the place of the old message (i.e. far in the past) without 
the freshness mark ("."). 

In my case, either I miss some messages or, if I knew how many fresh mails 
were waiting for me thanks to another program, I loose some time looking 
for my invisible fresh mails, fail to spot them, and decide to switch to 
unthreaded view (M-C-t) where articles are sorted correctly.

Any idea ?