diff --git a/callback.c b/callback.c
index a52e36e..4720007 100644
--- a/callback.c
+++ b/callback.c
@@ -3,12 +3,13 @@
 
 #include "tree.h"
 #include "contain.h"
+#include "dialog.h"
 #include "texts.h"
 #include "in_depth.h"
 #include "parsing.h"
 #include "graph_area.h"
 
-static GtkWindow *main_window;
+static GtkWindow *main_window, *dialog_window;
 
 /******************************************************************************/
 /*                M A I N   W I N D O W   A C T I V A T I O N                 */
@@ -22,6 +23,18 @@ void on_main_window_activation (GtkApplication *self, gpointer user_data)
   gtk_window_present (GTK_WINDOW (main_window));
 }
 
+void on_dialog_window_activation (GtkApplication *self, gpointer user_data)
+{
+  dialog_window = GTK_WINDOW (gtk_application_window_new (self));
+  dialog_window_child (dialog_window,0); //  0 is the state page (see contain.c)
+  dialog_window_header_bar (dialog_window, "dialog window");
+//  gtk_window_set_modal (GTK_WINDOW (dialog_window), TRUE);
+  gtk_window_set_transient_for (GTK_WINDOW (dialog_window), GTK_WINDOW (main_window));
+  gtk_window_set_destroy_with_parent (GTK_WINDOW (dialog_window), TRUE);
+  gtk_window_set_deletable (GTK_WINDOW (dialog_window), FALSE); //  FALSE
+  gtk_window_present (GTK_WINDOW (dialog_window));
+}
+
 void on_auto_notification (const char *message)
 {
   /*  Ignored  (2024-06-06)  because I don't know how to get "main_window" easily
diff --git a/callback.h b/callback.h
index e0778ee..f6c2a43 100644
--- a/callback.h
+++ b/callback.h
@@ -2,6 +2,7 @@
 
 
 void on_main_window_activation (GtkApplication *app, gpointer user_data);
+void on_dialog_window_activation (GtkApplication *self, gpointer user_data);
 void on_auto_notification (const char *message);
 
 void on_user_tree_expander_toggled (GtkExpander *expander, gpointer user_data);
diff --git a/dialog.c b/dialog.c
new file mode 100644
index 0000000..3c876d7
--- /dev/null
+++ b/dialog.c
@@ -0,0 +1,19 @@
+#include <stdio.h>
+#include <gtk-4.0/gtk/gtk.h>
+
+#include "callback.h"
+#include "in_depth.h"
+#include "display.h"
+#include "tree.h"
+#include "texts.h"
+
+// https://docs.gtk.org/gtk4/visual_index.html  <  widgets gallery
+
+
+void dialog_window_child (GtkWindow *dialog_window, int selected_page){}
+
+void dialog_window_header_bar (GtkWindow *dialog_window, char *title){
+  GtkWidget *header_bar = GTK_WIDGET (gtk_header_bar_new ());
+  gtk_header_bar_set_title_widget (GTK_HEADER_BAR (header_bar), gtk_label_new (title));
+  gtk_window_set_titlebar (dialog_window, header_bar);
+}
diff --git a/dialog.h b/dialog.h
new file mode 100644
index 0000000..9d8a58e
--- /dev/null
+++ b/dialog.h
@@ -0,0 +1,5 @@
+#include <gtk-4.0/gtk/gtk.h>
+
+void dialog_window_header_bar (GtkWindow *dialog_window, char *title);
+void dialog_window_child (GtkWindow *dialog_window, int selected_page);
+
diff --git a/in_depth.c b/in_depth.c
index 7932ed9..98499e0 100644
--- a/in_depth.c
+++ b/in_depth.c
@@ -10,16 +10,14 @@
 // (exec / edit) X (state / rules / measure) X (observ / interpret / read / write)
 
 enum {  //  S T A T E S
+  INTER,
   EXEC_STOP,
   EXEC_RUN,
-  EXEC_STOP_EDIT_RULE,
-  EXEC_RUN_EDIT_RULE,
-  EXEC_STOP_EDIT_MEASURE,
-  EXEC_RUN_EDIT_MEASURE,
   EDIT_STATE,
   EDIT_RULE,
+  MEASURE,
   OBSERVE,
-  INTERPRET,
+  ANALYSE,
   HELP,
   CONFIGURE
 };
@@ -29,23 +27,35 @@ static int status = EXEC_STOP; // int  get_status () {return status;}
 enum {  //  T R A N S I T I O N S
   EXEC_TO_RUN,
   RUN_TO_EXEC,
+  EXEC_TO_INTER,
+  INTER_TO_EDIT,
+  EDIT_TO_INTER,
+  INTER_TO_EXEC,
 };
 /******************************************************************************/
 /*                          T R A N S I T I O N S                             */
 /******************************************************************************/
 
-void let_transition_be (int asked) {
+void SWITCH_TO (int asked) {
   switch (asked) {
   case (0) :  //  EXEC_TO_RUN
     status = EXEC_RUN;
     break;
   case (1) :  //  RUN_TO_EXEC
+    status = EXEC_STOP;
+    break;
+  case (2) :  //  EXEC_TO_INTER
+    status = INTER;
+    break;
+  case (3) :  //  EDIT_TO_INTER
     //   Ici, il faudra prévenir l'utilisateur par une pop-up window :   TODO   (sauvegarde automatique sinon)
     //   S'il ne prend pas la main, les données de la simulation en cours risquent d'être perdues
-    status = EXEC_STOP;
+    status = INTER;
     break;
   default : ;
   }
+
+//q  gtk_window_present (GTK_WINDOW (main_window));
 }
 
 
diff --git a/main.c b/main.c
index 32ccfc3..bd2de6e 100644
--- a/main.c
+++ b/main.c
@@ -16,6 +16,7 @@ int main (int argc, char **argv)
 
   app = gtk_application_new ("org.jean.GTK4_GG_hack", G_APPLICATION_DEFAULT_FLAGS);
   g_signal_connect (app, "activate", G_CALLBACK (on_main_window_activation), NULL);
+  g_signal_connect (app, "activate", G_CALLBACK (on_dialog_window_activation), NULL);
   status = g_application_run (G_APPLICATION (app), argc, argv);
   g_object_unref (app);