-VikLayer *vik_layer_create ( VikLayerTypeEnum type, gpointer vp, GtkWindow *w, gboolean interactive )
+time_t vik_layer_get_timestamp ( VikLayer *vl )
+{
+ if ( vik_layer_interfaces[vl->type]->get_timestamp )
+ return vik_layer_interfaces[vl->type]->get_timestamp ( vl );
+ return 0;
+}
+
+VikLayer *vik_layer_create ( VikLayerTypeEnum type, VikViewport *vp, gboolean interactive )