- (let ((level (gnus-summary-thread-level)))
- (while (and (gnus-summary-set-process-mark (gnus-summary-article-number))
- (zerop (gnus-summary-next-subject 1))
- (> (gnus-summary-thread-level) level))))
+ (gnus-save-hidden-threads
+ (let ((level (gnus-summary-thread-level)))
+ (while (and (gnus-summary-set-process-mark
+ (gnus-summary-article-number))
+ (zerop (gnus-summary-next-subject 1 nil t))
+ (> (gnus-summary-thread-level) level)))))