diff --git a/sw/logalizer/Makefile b/sw/logalizer/Makefile
index b3963d29b9..c5dbcff720 100644
--- a/sw/logalizer/Makefile
+++ b/sw/logalizer/Makefile
@@ -29,7 +29,7 @@ INCLUDES= -I +xml-light
 
 all: play plotter plot
 
-play : play.ml
+play : log_file.ml play.ml
 	@echo OL $@
 	$(Q)$(OCAMLC) $(INCLUDES) -custom -o $@ unix.cma str.cma xml-light.cma glibivy-ocaml.cma -I +lablgtk2 -I ../lib/ocaml lablgtk.cma lib-pprz.cma gtkInit.cmo  $^
 
@@ -37,7 +37,7 @@ plotter : plotter.ml
 	@echo OL $@
 	$(Q)$(OCAMLC) $(INCLUDES) -custom -o $@ unix.cma str.cma xml-light.cma glibivy-ocaml.cma -I +lablgtk2 -I ../lib/ocaml lablgtk.cma lib-pprz.cma gtkInit.cmo  $^
 
-plot : plot.ml
+plot : log_file.ml plot.ml
 	@echo OL $@
 	$(Q)$(OCAMLOPT) $(INCLUDES) -o $@ unix.cmxa str.cmxa xml-light.cmxa glibivy-ocaml.cmxa -I +lablgtk2 -I ../lib/ocaml lablgtk.cmxa lib-pprz.cmxa gtkInit.cmx  $^
 
diff --git a/sw/logalizer/log_file.ml b/sw/logalizer/log_file.ml
new file mode 100644
index 0000000000..d976c15053
--- /dev/null
+++ b/sw/logalizer/log_file.ml
@@ -0,0 +1,79 @@
+(*
+ * $Id$
+ *
+ * Log files utilities
+ *  
+ * Copyright (C) 2007 ENAC
+ *
+ * This file is part of paparazzi.
+ *
+ * paparazzi is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * paparazzi is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with paparazzi; see the file COPYING.  If not, write to
+ * the Free Software Foundation, 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA. 
+ *
+ *)
+
+open Printf
+
+let (//) = Filename.concat
+
+let logs_dir = Env.paparazzi_home // "var" // "logs"
+
+let log_suffix = fun s ->
+  let n = String.length s in
+  n > 4 && String.sub s (n-4) 4 = ".log"
+
+let length_data = fun data_file ->
+  let f = Ocaml_tools.open_compress data_file in
+  let line = ref "" in
+  try
+    while true do line := input_line f done; failwith "unreachable"
+  with
+    End_of_file ->
+      let i = String.index !line '.' in
+      int_of_string (String.sub !line 0 i)
+
+let chooser = fun ~callback () ->
+  let dialog = GWindow.file_chooser_dialog ~action:`OPEN ~title:"Open Log" () in
+  ignore (dialog#set_current_folder logs_dir);
+  dialog#add_filter (GFile.filter ~name:"log" ~patterns:["*.log"] ());
+  dialog#add_button_stock `CANCEL `CANCEL ;
+  dialog#add_select_button_stock `OPEN `OPEN ;
+  let info_label = GMisc.label ~text:"1234" () in
+  dialog#set_extra_widget info_label#coerce;
+
+  let preview_cb = fun () ->
+    match dialog#preview_filename with
+    | Some log_file when log_suffix log_file ->
+	let basename = Filename.chop_extension (Filename.basename log_file) in
+	let data_file = basename ^ ".data" in
+	let info =
+	  try
+	    let data_file = Ocaml_tools.find_file [Filename.dirname log_file] data_file in
+	    let size = (Unix.stat data_file).Unix.st_size / 1000 in
+	    let time = length_data data_file in
+	    sprintf "Data Size: %dk, Time Length: %ds" size time
+	  with
+	    Not_found -> "No associated data file found" in
+	info_label#set_text (sprintf "Log %s: %s" basename info)
+    | _ -> info_label#set_text "" in
+	
+  ignore(dialog#connect#update_preview ~callback:preview_cb);
+
+  begin match dialog#run (), dialog#filename with
+    `OPEN, Some name ->
+      dialog#destroy ();
+      callback name
+  | _ -> dialog#destroy ()
+  end
diff --git a/sw/logalizer/play.ml b/sw/logalizer/play.ml
index 6d2eeecdb4..b667dfc909 100644
--- a/sw/logalizer/play.ml
+++ b/sw/logalizer/play.ml
@@ -30,7 +30,6 @@ module Ground_Pprz = Pprz.Messages(struct let name = "ground" end)
 
 let (//) = Filename.concat
 let replay_dir = Env.paparazzi_home // "var" // "replay"
-let logs_dir = Env.paparazzi_home // "var" // "logs"
 let dump_fp = Env.paparazzi_src // "sw" // "tools" // "gen_flight_plan.out -dump"
 
 
@@ -120,22 +119,10 @@ let stop = fun () ->
   | Some t -> GMain.Timeout.remove t; timer := None
 
 
-let file_dialog ~title ~callback () =
-  let dialog = GWindow.file_chooser_dialog ~action:`OPEN ~title () in
-  ignore (dialog#set_current_folder logs_dir);
-  dialog#add_filter (GFile.filter ~name:"log" ~patterns:["*.log"] ());
-  dialog#add_button_stock `CANCEL `CANCEL ;
-  dialog#add_select_button_stock `OPEN `OPEN ;
-  begin match dialog#run (), dialog#filename with
-    `OPEN, Some name ->
-      dialog#destroy ();
-      callback name
-  | _ -> dialog#destroy ()
-  end
 
 let open_log = fun window adj () ->
   stop ();
-  ignore (file_dialog ~title:"Open Log" ~callback:(fun name -> load_log window adj name) ())
+  ignore (Log_file.chooser ~callback:(fun name -> load_log window adj name) ())
 
 let index_of_time log t =
   let t = t in
diff --git a/sw/logalizer/plot.ml b/sw/logalizer/plot.ml
index a7c8c8f98a..30bd26329f 100644
--- a/sw/logalizer/plot.ml
+++ b/sw/logalizer/plot.ml
@@ -443,21 +443,8 @@ let load_log = fun ?factor (plot:plot) (menubar:GMenu.menu_shell GMenu.factory)
 
 
 
-let file_dialog ~title ~callback () =
-  let dialog = GWindow.file_chooser_dialog ~action:`OPEN ~title () in
-  ignore (dialog#set_current_folder logs_dir);
-  dialog#add_filter (GFile.filter ~name:"log" ~patterns:["*.log"] ());
-  dialog#add_button_stock `CANCEL `CANCEL ;
-  dialog#add_select_button_stock `OPEN `OPEN ;
-  begin match dialog#run (), dialog#filename with
-    `OPEN, Some name ->
-      dialog#destroy ();
-      callback name
-  | _ -> dialog#destroy ()
-  end
-
 let open_log = fun ?factor plot menubar curves_fact () ->
-  ignore (file_dialog ~title:"Open Log" ~callback:(fun name -> load_log ?factor plot menubar curves_fact name) ())
+  ignore (Log_file.chooser ~callback:(fun name -> load_log ?factor plot menubar curves_fact name) ())
 
 
 let remove_fst_and_snd = function