[glom] Mention the GTK+3 bug in the ChangeLog

[Murray Cumming <murrayc src gnome org>]

commit 8b3bfcd09be7303e8e3a88c79a249f76b21fed13
Author: Murray Cumming <murrayc murrayc com>
Date:   Fri Oct 28 10:06:48 2011 +0200

    Mention the GTK+3 bug in the ChangeLog

 ChangeLog |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index ee68089..724c1dd 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -15,7 +15,7 @@
 	Gtk::Frame::unset_label() instead of just hiding the frame's label,
 	because that apparently leads to an incorrect allocation, causing the 
 	buttons to be cut in half horizontally at the bottom.
-	I will investigate.
+	This is caused by a regression in GTK+ 3: See bug #662915
 
 1.19.16: