+(defun notmuch-tree-goto-matching-message (&optional prev)
+ "Move to the next or previous matching message.
+
+Returns t if there was a next matching message in the thread to show,
+nil otherwise."
+ (let ((dir (if prev -1 nil))
+ (eobfn (if prev #'bobp #'eobp)))
+ (while (and (not (funcall eobfn))
+ (not (notmuch-tree-get-match)))
+ (forward-line dir))
+ (not (funcall eobfn))))
+