@sareed: I checked in views template, but not found.

@No Sssweat: Class is an option if there is no other solution, but getElementByClassName is less supported by browsers than getElementById.

Ok, in fact when $variables['theme_hook_suggestions'][] = "block__XXX_YYY"; drupal looks for template file block--XXX-YYY.tpl.php. Strange because I did the same for html template using html--XXX--YYY as suggestion and html--XXX-YYY.tpl.php as template file name without any problem. I will ask a question about that.

Thanks rooby, it is what I was looking for, now I don't understand why drupal is still calling the default block.tpl.php instead of my custom one set in the preprocess function. I'm still debugging to understand that...

@MrUpsidown: yes I do, but I don't think I may call my theme function which build the new link from there. Perhaps I'm wrong.

@MrUpsidown: rewriting is not an option at least because I need to get/extract the contextual filter values that have been given as parameters to call this view. Then I insert other parameters like computed page number to build the new link for the image.