Introduce state manager (fixes #119)

Change-Id: Idfd71ea53a898c57e676a197776e2b019ef08561
diff --git a/Changes b/Changes
index c3356f3..6bcc53d 100755
--- a/Changes
+++ b/Changes
@@ -41,6 +41,7 @@
         - Introduce pagination panel.
         - Support for inactive buttongroup items.
         - Support default values for state.
+        - Introduce state manager (#119).
 
 0.42 2021-06-18
         - Added GitHub based CI for perl.