docs: Add another cross reference

Refer to the new coordinate system overview
from the GdkEvent docs.

diff --git a/gdk/gdkevents.c b/gdk/gdkevents.c
index 1353da6eacbab50ee3d708ab31b85da9f40c5643..676f0c9df1bca24fb73d028c0d03203824f7c817 100644 (file)
--- a/gdk/gdkevents.c
+++ b/gdk/gdkevents.c
@@ -1371,6 +1371,8 @@ gdk_event_get_modifier_state (GdkEvent *event)
  * @y: (out): location to put event surface y coordinate
  *
  * Extract the event surface relative x/y coordinates from an event.
+ *
+ * This position is in [surface coordinates](coordinates.html).
  */
 gboolean
 gdk_event_get_position (GdkEvent *event,