-(defun notmuch-show (thread-id)
- "Run \"notmuch show\" with the given thread ID and display results."
+(defun notmuch-show (thread-id &optional parent-buffer)
+ "Run \"notmuch show\" with the given thread ID and display results.
+
+The optional PARENT-BUFFER is the notmuch-search buffer from
+which this notmuch-show command was executed, (so that the next
+thread from that buffer can be show when done with this one)."