viewer: fix build on 'old' GTK2

Debian lenny has gtk2 2.12.12, which is missing gtk_widget_get_window.
Provide our own function if GTK2 <= 2.12 .

Highly inspired from: http://osdir.com/ml/svn-commits-list/2009-08/msg00725.html

1 files changed, 3 insertions, 0 deletions

diff --git a/src/util.h b/src/util.h
index 421ea6c..dafd819 100644
--- a/src/util.h
+++ b/src/util.h
@@ -27,6 +27,9 @@
 #include <gtk/gtk.h>
 #include <glade/glade.h>
 
+#if (GTK_MAJOR_VERSION == 2 && GTK_MINOR_VERSION <= 12)
+#define gtk_widget_get_window(widget) ((widget)->window)
+#endif
 
 extern gboolean doDebug;