diff -up openbox-3.6/obrender/theme.h.abifix openbox-3.6/obrender/theme.h
--- openbox-3.6/obrender/theme.h.abifix	2015-01-12 20:48:27.000000000 +0100
+++ openbox-3.6/obrender/theme.h	2015-06-25 17:28:43.401411179 +0200
@@ -114,6 +114,8 @@ struct _RrTheme {
     RrColor *osd_pressed_lineart;
     RrColor *osd_focused_lineart;
     RrColor *menu_title_shadow_color;
+    /* padding to make libobrender compatible with openbox-3.5.2 */
+    void *_pad[8];
     RrColor *menu_text_shadow_color;
 
     /* style settings - pics */