(define (render-widgets sxml env default-bindings bindings contents)
  (let ((add-attr (lambda (attr) (environment-set! env (first attr) (second attr)))))
    (if (list? default-bindings) (for-each add-attr default-bindings))
    (if (list? bindings) (for-each add-attr bindings))
    (environment-set! env 'contents contents)
    (eval `(let ((++ string-append)) ,sxml) env))) ; Render the widget