--- a/hgext3rd/topic/__init__.py	Sat Sep 01 14:00:41 2018 +0200
+++ b/hgext3rd/topic/__init__.py	Mon Sep 03 16:29:02 2018 +0200
@@ -29,8 +29,10 @@
 your current topic.
 
 Topic is offering you aliases reference to changeset in your current topic
-stack as 't#'. For example, 't1' refers to the root of your stack, 't2' to the
-second commits, etc. The 'hg stack' command show these number.
+stack as 't#'. For example, 's1' refers to the root of your stack, 's2' to the
+second commits, etc. The 'hg stack' command show these number. 's0' can be used
+to refer to the parent of the topic root. Updating using `hg up s0` will keep
+the topic active.
 
 Push behavior will change a bit with topic. When pushing to a publishing
 repository the changesets will turn public and the topic data on them will fade
@@ -253,12 +255,23 @@
         return None
 context.basectx.topicidx = _contexttopicidx
 
+stackrev = re.compile(r'^s\d+$')
 topicrev = re.compile(r'^t\d+$')
 branchrev = re.compile(r'^b\d+$')
 
 def _namemap(repo, name):
     revs = None
-    if topicrev.match(name):
+    if stackrev.match(name):
+        idx = int(name[1:])
+        tname = topic = repo.currenttopic
+        if topic:
+            ttype = 'topic'
+            revs = list(stack.stack(repo, topic=topic))
+        else:
+            ttype = 'branch'
+            tname = branch = repo[None].branch()
+            revs = list(stack.stack(repo, branch=branch))
+    elif topicrev.match(name):
         idx = int(name[1:])
         ttype = 'topic'
         tname = topic = repo.currenttopic
@@ -1174,7 +1187,7 @@
 
 def checkt0(orig, ui, repo, node=None, rev=None, *args, **kwargs):
 
-    thezeros = set(['t0', 'b0'])
+    thezeros = set(['t0', 'b0', 's0'])
     backup = repo.ui.backupconfig('_internal', 'keep-topic')
     try:
         if node in thezeros or rev in thezeros: