clock: document that GstClockEntry should be treated as ana opaque structure.

diff --git a/gst/gstclock.h b/gst/gstclock.h
index 8710dfa..f83face 100644 (file)
--- a/gst/gstclock.h
+++ b/gst/gstclock.h
@@ -335,6 +335,8 @@ typedef enum {
  *
  * All pending timeouts or periodic notifies are converted into
  * an entry.
+ * Note that GstClockEntry should be treated as an opaque structure. It must
+ * not be extended or allocated using a custom allocator.
  */
 struct _GstClockEntry {
   gint                 refcount;