Hmmm, doing a find in files for "public static function isInt" to try to find the validation class (or optionally hitting ctrl+N and looking for the ValidateCore class) is not what I want... I want autocomplete for Validate::(I need the "isDecimal" version).
Julien Bourdeau has the solution, PhpStorm-PrestaShop-Autocomplete. Quick install and just works. Thanks, Julien!
Ah! It's "Validate::isFloat".