Version 2 numbering

Hi guys,

I'm a bit confused about the "version 2" numbering for libatk.  I 
noticed this morning that a new branch got created for version 3 (the 
new branch is called "gnome-3-12") and I assume that it's timed to match 
similar libraries (such as glib / glibmm etc) who also just released 
version 3.12

However....  the latest atk branch I can find for version 2 is 
"gnome-2-30" - even though glib and glibmm are now 5 x releases further 
on, at ver 2.40.  Glib and Gtk seem to be developing versions 2 and 3 in 
parallel.  Is that not the case for atk or is there some other 
explanation for why the version 2 branches haven't moved on since 2.30?  
It's not a big problem.  I'm just curious to understand the difference.  
Thanks.

John