Debugger entered--Lisp error: (wrong-type-argument sequencep 116)
  mapconcat(#[(mark) "\302\303	\"\243\304\"\207" [mark gnus-registry-marks plist-get assoc :char] 4] (To-Do) "")
  gnus-user-format-function-M([36485 "courier" "Uwe Brauer <oub@mat.ucm.es>" #("Mon, 20 Feb 2017 23:04:28 +0000" 0 1 (gnus-time (22699 30204))) "<58AB75FC.3090705@mat.ucm.es>" nil 10127 21 nil ((To . "Uwe Brauer <oub@mat.ucm.es>"))])
  (format "[%s]%c%c%c%s%d " (gnus-user-format-function-M gnus-tmp-header) gnus-tmp-unread gnus-tmp-replied gnus-tmp-score-char gnus-tmp-indentation (aref gnus-tmp-header 0))
  (insert (format "[%s]%c%c%c%s%d " (gnus-user-format-function-M gnus-tmp-header) gnus-tmp-unread gnus-tmp-replied gnus-tmp-score-char gnus-tmp-indentation (aref gnus-tmp-header 0)))
  (progn (insert (format "[%s]%c%c%c%s%d " (gnus-user-format-function-M gnus-tmp-header) gnus-tmp-unread gnus-tmp-replied gnus-tmp-score-char gnus-tmp-indentation (aref gnus-tmp-header 0))) (put-text-property (point) (progn (insert (format "%c %-10s%c" gnus-tmp-opening-bracket (let* ((val ...) (need ...)) (if (> need 0) (concat nil val ...) val)) gnus-tmp-closing-bracket)) (point)) (quote mouse-face) gnus-mouse-face) (insert (format " %-10s  [%-25s%c %s %s %s   \n" (let* ((val (eval (let ... ...))) (need (- 10 (string-width val)))) (if (> need 0) (concat nil val (make-string need 32)) val)) (let* ((val (eval (if ... ... gnus-tmp-subject-or-nil))) (need (- 25 (string-width val)))) (if (> need 0) (concat nil val (make-string need 32)) val)) gnus-tmp-closing-bracket (aref gnus-tmp-header 3) (
 gnus-summary-line-message-size gnus-tmp-header) gnus-tmp-lines)))
  eval((progn (insert (format "[%s]%c%c%c%s%d " (gnus-user-format-function-M gnus-tmp-header) gnus-tmp-unread gnus-tmp-replied gnus-tmp-score-char gnus-tmp-indentation (aref gnus-tmp-header 0))) (put-text-property (point) (progn (insert (format "%c %-10s%c" gnus-tmp-opening-bracket (let* ((val ...) (need ...)) (if (> need 0) (concat nil val ...) val)) gnus-tmp-closing-bracket)) (point)) (quote mouse-face) gnus-mouse-face) (insert (format " %-10s  [%-25s%c %s %s %s   \n" (let* ((val (eval (let ... ...))) (need (- 10 (string-width val)))) (if (> need 0) (concat nil val (make-string need 32)) val)) (let* ((val (eval (if ... ... gnus-tmp-subject-or-nil))) (need (- 25 (string-width val)))) (if (> need 0) (concat nil val (make-string need 32)) val)) gnus-tmp-closing-bracket (aref gnus-tmp-header
  3) (gnus-summary-line-message-size gnus-tmp-header) gnus-tmp-lines))))
  gnus-summary-prepare-threads((([36485 "courier" "Uwe Brauer <oub@mat.ucm.es>" #("Mon, 20 Feb 2017 23:04:28 +0000" 0 1 (gnus-time (22699 30204))) "<58AB75FC.3090705@mat.ucm.es>" nil 10127 21 nil ((To . "Uwe Brauer <oub@mat.ucm.es>"))])))
  gnus-rebuild-thread("<58AB75FC.3090705@mat.ucm.es>" nil)
  gnus-summary-insert-subject("<58AB75FC.3090705@mat.ucm.es>" [36485 "courier" "Uwe Brauer <oub@mat.ucm.es>" #("Mon, 20 Feb 2017 23:04:28 +0000" 0 1 (gnus-time (22699 30204))) "<58AB75FC.3090705@mat.ucm.es>" nil 10127 21 nil ((To . "Uwe Brauer <oub@mat.ucm.es>"))])
  gnus-summary-update-article(36485 (36485 79 7726 [36485 "courier" "Uwe Brauer <oub@mat.ucm.es>" #("Mon, 20 Feb 2017 23:04:28 +0000" 0 1 (gnus-time (22699 30204))) "<58AB75FC.3090705@mat.ucm.es>" nil 10127 21 nil ((To . "Uwe Brauer <oub@mat.ucm.es>"))] 0))
  gnus-registry--set/remove-mark(To-Do nil (36485))
  gnus-registry-set-article-To-Do-mark(36485)
  funcall-interactively(gnus-registry-set-article-To-Do-mark 36485)
  call-interactively(gnus-registry-set-article-To-Do-mark nil nil)
  command-execute(gnus-registry-set-article-To-Do-mark)