Changing TABS into CONTEXTUAL LINKS
I found a sollution to overwrite the "theme_menu_local_tasks" function.

function MODULENAME_theme_registry_alter(&amp;$theme_registry) {
    if (!empty($theme_registry['form_element'])) {
        // Menu local tasks
        $theme_registry['menu_local_tasks']['function'] = 'MODULENAME_menu_local_tasks';
    }
}