Im using also avatars in member list / viewonline, so i added the necessary changes here:
http://www.phpbb.com/community/viewtopi ... 5#p6657245
And avatars in friend list too
http://www.phpbb.com/community/viewtopi ... 5#p6656845
Those are just quick fix for making it work with those mods in particular
But i believe any other mod would need to be adapted too, when you use the get_avatar function, generaly you also look at user row for size and type for other operations (like resize...), so what it would need is to set all variables on the fly for no_avatar in case its empty, instead of just giving the image, i didnt figured out at all how it would be possible, any idea ?
Edit: i just tested to see and its working without adjustements for blog, arcade room, i believe it should work with most that dont make any operation on avatar and just use get_avatar function, so its not as bad as i described, tough the question is still valid lol