[gimp] Require GTK+ >= 2.16.6

[Michael Natterer <mitch src gnome org>]

commit 699b112940cd3cbf3600c37e1abdb4f06243768e
Author: Michael Natterer <mitch gimp org>
Date:   Wed Sep 16 22:04:17 2009 +0200

    Require GTK+ >= 2.16.6
    
    That version contains a GtkTreeView fix essential to group layers.

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index c9bab59..6b35c14 100644
--- a/configure.ac
+++ b/configure.ac
@@ -43,7 +43,7 @@ m4_define([gimp_full_name], [GNU Image Manipulation Program])
 m4_define([babl_required_version], [0.1.0])
 m4_define([gegl_required_version], [0.1.0])
 m4_define([glib_required_version], [2.20.0])
-m4_define([gtk_required_version], [2.16.1])
+m4_define([gtk_required_version], [2.16.6])
 m4_define([gdk_pixbuf_required_version], [gtk_required_version])
 m4_define([cairo_required_version], [1.6.0])
 m4_define([pangocairo_required_version], [1.20.1])