diff --git a/gtk/gtkthemingengine.c b/gtk/gtkthemingengine.c
index 886fc8f5ca..59cfcd3dd3 100644
--- a/gtk/gtkthemingengine.c
+++ b/gtk/gtkthemingengine.c
@@ -45,6 +45,10 @@
  * must be created, alongside the CSS file that will reference it, the
  * theming engine would be created as an .so library, and installed in
  * $(gtk-modules-dir)/theming-engines/.
+ *
+ * #GtkThemingEngine<!-- -->s have limited access to the object they are
+ * rendering, the #GtkThemingEngine API has read-only accessors to the
+ * style information contained in the rendered object's #GtkStyleContext.
  */
 
 typedef struct GtkThemingEnginePrivate GtkThemingEnginePrivate;