diff -r 8e4be44a676f -r 3af4b39afe2a mercurial/util.py
--- a/mercurial/util.py	Wed Jan 06 21:11:58 2010 +0100
+++ b/mercurial/util.py	Sun Jan 10 18:13:34 2010 +0100
@@ -529,6 +529,14 @@
 def lookup_reg(key, name=None, scope=None):
     return None
 
+def hidewindow():
+    """Hide current shell window.
+
+    Used to hide the window opened when starting asynchronous
+    child process under Windows, unneeded on other systems.
+    """
+    pass
+
 if os.name == 'nt':
     from windows import *
 else: