Index: select.h
===================================================================
--- select.h	(revision 33499)
+++ select.h	(revision 33500)
@@ -43,8 +43,14 @@
 long int *pcb_list_block(pcb_board_t *pcb, rnd_box_t *Box, int *len);
 
 /* List visible objects on screen within a box; return number of objects, call
-   a callback on each object found. Optionally limit the search to specific layer types plus globals */
+   a callback on each object found. Always creates the return list (caller must
+   free it) and always redraws objects */
 int pcb_list_block_cb(pcb_board_t *pcb, rnd_box_t *Box, void *(cb)(void *ctx, pcb_any_obj_t *obj), void *ctx);
+
+/* Same as above, except:
+   - limit the search to specific layer types plus globals
+   - if cb is not NULL, do not create the return list (and do not redraw)
+*/
 int pcb_list_lyt_block_cb(pcb_board_t *pcb, pcb_layer_type_t lyt, rnd_box_t *Box, void *(cb)(void *ctx, pcb_any_obj_t *obj), void *ctx);