(define-method (set-attribute (ih <IHandle>) (key <keyword>) (value <string>))
  ((setter attributes) ih (alist-cons key value (attributes ih)))
  (#~IupSetAttribute pointer: (ptr ih) string: (string-upcase (keyword->string key)) string: value))
(define-method (get-attribute (ih <IHandle>) (key <keyword>))
  (#~IupGetAttribute (ptr ih) string: (string-upcase (keyword->string key)) return: string:))