extern bool fgHasNode (const char * path);
+/**
+ * Add a listener to a node.
+ *
+ * @param listener The listener to add to the node.
+ * @param path The path of the node, relative to root.
+ * @param index The index for the last member of the path (overrides
+ * any given in the string).
+ */
+extern void fgAddChangeListener (SGPropertyChangeListener * listener,
+ const char * path);
+
+
+/**
+ * Add a listener to a node.
+ *
+ * @param listener The listener to add to the node.
+ * @param path The path of the node, relative to root.
+ * @param index The index for the last member of the path (overrides
+ * any given in the string).
+ */
+extern void fgAddChangeListener (SGPropertyChangeListener * listener,
+ const char * path, int index);
+
+
/**
* Get a bool value for a property.
*