How do I override the content region for a specific page? I want to override the content region for a specific page, but using the hook page--mypage--region--content.tpl.php won't work. How should I name it?

My site supports block override, I tested this with a dummy region.tpl.php and I currently use a custom page.tpl.php.
For this you have to override preprocess region

function MYTHEME_preprocess_region(&amp;$variables) {
    if(CONDITION){
        $variables['theme_hook_suggestions'][] = 'regionspecial__' . $variables['region'];
    }
    print_r($variables['theme_hook_suggestions']); // comment this statement
}


After that your template suggestion name will be 'regionspecial--content.tpl.php' For certain desired condition.  Once you clear Drupal's caches your new template file should start being used for that region. It might be worth noting that you'll probably need a copy of the core region.tpl.php file somewhere in your theme folder as well, or the theme registry might not pick up your custom file.