Compiled Template file names with $use_sub_dirs = false

Hi :) I just recognized that compiled templates don't have a .php extension if I have $smarty->use_sub_dirs set to false... Is this a feature? ;) Would be nice if they had .php extension, as then for example PHP Syntax Highlighting would work better in some Editors etc... And it's a question of consistency, too, because with $smarty->use_sub_dirs = true, compiled templates do have .php extensions... :) David P.S: why isn't there a (un)register_insert() function? :)