Olivier,

Instead of 

$('#q12').focus(function(){
    //your code here
});

Try

$('#q12 input').focus(function(){
    //your code here
});

My guess is it isn't working because the ID is attached to the parent rather than the actual input field so that event you're currently targeting doesn't actually fire.

If you are using something other than an input, replace input with the appropriate element type (select, textarea, etc.).

Keyup, keydown, etc. are working because those events happen within the scope of the parent, but others are limited to the actual input element.