I've used the shadowbox-js plugin for WordPress for some years and since version 3.9 WordPress has decided not to output a title attribute in the image code, citing 'accessibility' as a reason. I doubt if it's just shadowbox that's affected, the title is used by many gallery plugins to caption images amongst other things.
So, can shadowbox be made to use the alt tag instead? I've been trying for some time but no joy as yet.
Utillising the captioning hack looked like a possible solution but apart from not being able to make it work i thought the alt tag would be a slicker way, especially in WordPress 'native' galleries.