Thus far, at least on the Windows builds while the UI is graphically correct, the GTK Widget Layout seems to need additional annotation to retain correct UNO Accessibility API roles.

Version: 4.2.0.0.alpha0+
Build ID: 164b6ce7b27c0a9ec19019e7b078b9f8f382007d
TinderBox: Win-x86@39, Branch:master, Time: 2013-09-28_16:39:42 

The GTK Widget Layout implemented for Start Center and Template Manager has some annoying UNO Accessibility API flaws in that the ThumbnailView List correctly names only the first item in the list--and all "descendant" items on the list receive the same "name". And with keyboard cursor key <L,R,U,D> navigation through the list, only the first item will receive focus and update. Each additional list item will not receive focus, nor refresh its "name".
   
Expected result:

As the Thumbnail View list is traversed, correct index is kept, correct role is assigned, and parent name and role are correctly reported.

Someone with a current Linux build of Master should probably check behavior under ORCA and Accerciser. Same for a round with NSAccessibility on OS X with a current build of master.