CenterBox: Guard against directly including header

https://bugzilla.gnome.org/show_bug.cgi?id=785280

diff --git a/gtk/gtkcenterbox.h b/gtk/gtkcenterbox.h
index 4c8e7ad21a3f5e166be86373b8f4875687783f01..bfd68f80e975b7d830dca64576b49afb0600a8e0 100644 (file)
--- a/gtk/gtkcenterbox.h
+++ b/gtk/gtkcenterbox.h
@@ -22,6 +22,10 @@
 #ifndef __GTK_CENTER_BOX_H__
 #define __GTK_CENTER_BOX_H__
 
+#if !defined (__GTK_H_INSIDE__) && !defined (GTK_COMPILATION)
+#error "Only <gtk/gtk.h> can be included directly."
+#endif
+
 #include "gtkwidget.h"
 
 G_BEGIN_DECLS