diff --git a/README.in b/README.in
index e5d4249fef..6c109dbd4b 100644
--- a/README.in
+++ b/README.in
@@ -92,6 +92,11 @@ Release notes for 3.12
   it used to inconsistently scroll with the buffer but then go
   reposition to a window-relative position on redraw.
 
+* A number of container widgets have been made more compliant with
+  the uniform CSS rendering model by making them render backgrounds
+  and borders. This may require some adjustments in applications that
+  were making assumptions about containers never rendering backgrounds.
+
 Release notes for 3.10
 ======================