diff --git a/callback.c b/callback.c
index 5720a7b..1a5e290 100644
--- a/callback.c
+++ b/callback.c
@@ -1,36 +1,22 @@
 #include <stdio.h>
 #include <gtk-4.0/gtk/gtk.h>
 
-#include "hot.h"
+#include "tree.h"
 #include "display.h"
 #include "contain.h"
 #include "texts.h"
+#include "in_depth.h"
 
 /******************************************************************************/
-/*    W I N D O W    (H E A D E R   B A R   &   T W O   N O T E B O O K S )   */
+/*                M A I N   W I N D O W   A C T I V A T I O N                 */
 /******************************************************************************/
-void activate (GtkApplication *self, gpointer user_data)
+void ui_main_window (GtkApplication *self, gpointer user_data)
 {
-  GtkWindow *window = GTK_WINDOW (gtk_application_window_new (self));
-  window_header_bar (window, "E coli   (with permission from David S. Goodsell, 2009)");
-  two_notebooks_in_two_panes (window);
-  gtk_window_present (GTK_WINDOW (window));
-}
-
-/******************************************************************************/
-/*                             B U T T O N S                                  */
-/******************************************************************************/
-void ui_toggle_run_edit (GtkWidget *btt_run_xor_edit, gpointer   data)
-{
-  printf("window.ui_toggle_run_edit()   >>>    mode = %d", get_run_edit_mode ());
-  if (get_run_edit_mode()) {
-    gtk_button_set_icon_name (GTK_BUTTON (btt_run_xor_edit), "system-run-symbolic");
-    set_run_edit_mode (0);
-  } else {
-    gtk_button_set_icon_name (GTK_BUTTON (btt_run_xor_edit), "document-edit-symbolic");
-    set_run_edit_mode (1);
-  }
-  printf(" > %d\n", get_run_edit_mode ());
+  GtkWindow *main_window = GTK_WINDOW (gtk_application_window_new (self));
+  window_header_bar (main_window,
+                     "E coli   (with permission from David S. Goodsell, 2009)");
+  two_notebooks_in_two_panes (main_window);
+  gtk_window_present (GTK_WINDOW (main_window));
 }
 
 /******************************************************************************/
@@ -60,3 +46,19 @@ void on_bind_user_tree_factory (GtkSignalListItemFactory *factory, GObject* obje
 //    } else if (0) printf("[on_bind_user_tree_factory] row == NULL\n");
 }
 
+/******************************************************************************/
+/*                             B U T T O N S                                  */
+/******************************************************************************/
+void ui_toggle_run_edit (GtkWidget *btt_run_xor_edit, gpointer   data)
+{
+  printf("window.ui_toggle_run_edit()   >>>    mode = %d", get_run_edit_mode ());
+  if (get_run_edit_mode()) {
+    gtk_button_set_icon_name (GTK_BUTTON (btt_run_xor_edit), "system-run-symbolic");
+    set_run_edit_mode (0);
+  } else {
+    gtk_button_set_icon_name (GTK_BUTTON (btt_run_xor_edit), "document-edit-symbolic");
+    set_run_edit_mode (1);
+  }
+  printf(" > %d\n", get_run_edit_mode ());
+}
+
diff --git a/callback.d b/callback.d
deleted file mode 100644
index 3913f5b..0000000
--- a/callback.d
+++ /dev/null
@@ -1,3 +0,0 @@
-callback.o: callback.c hot.h \
- /gnu/store/fkmpkdav2zmz1k72989bdgpdrfac7rz1-glib-2.78.0/include/glib-2.0/glib.h \
- display.h contain.h texts.h
diff --git a/callback.h b/callback.h
index 68f462a..46d6f7c 100644
--- a/callback.h
+++ b/callback.h
@@ -1,7 +1,7 @@
 //#include <stdio.h>
 #include <gtk-4.0/gtk/gtk.h>
 
-void activate (GtkApplication *app, gpointer user_data);
+void ui_main_window (GtkApplication *app, gpointer user_data);
 
 void ui_enable_action  (const char *name);
 void ui_disable_action (const char *name);
diff --git a/callback.o b/callback.o
deleted file mode 100644
index 79de046..0000000
Binary files a/callback.o and /dev/null differ
diff --git a/contain.c b/contain.c
index cbd9f51..6ce6ce3 100644
--- a/contain.c
+++ b/contain.c
@@ -1,7 +1,7 @@
 #include <stdio.h>
 #include <gtk-4.0/gtk/gtk.h>
 
-#include "hot.h"
+#include "tree.h"
 #include "display.h"
 #include "contain.h"
 #include "texts.h"
diff --git a/contain.d b/contain.d
deleted file mode 100644
index dc2d395..0000000
--- a/contain.d
+++ /dev/null
@@ -1,3 +0,0 @@
-contain.o: contain.c hot.h \
- /gnu/store/fkmpkdav2zmz1k72989bdgpdrfac7rz1-glib-2.78.0/include/glib-2.0/glib.h \
- display.h contain.h texts.h callback.h
diff --git a/contain.o b/contain.o
deleted file mode 100644
index 41e73b9..0000000
Binary files a/contain.o and /dev/null differ
diff --git a/display.c b/display.c
index ecfd724..d17a59d 100644
--- a/display.c
+++ b/display.c
@@ -1,7 +1,7 @@
 #include <stdio.h>
 #include <gtk-4.0/gtk/gtk.h>
 
-#include "hot.h"
+#include "tree.h"
 #include "display.h"
 #include "contain.h"
 #include "texts.h"
diff --git a/display.d b/display.d
deleted file mode 100644
index a8ba66f..0000000
--- a/display.d
+++ /dev/null
@@ -1,3 +0,0 @@
-display.o: display.c hot.h \
- /gnu/store/fkmpkdav2zmz1k72989bdgpdrfac7rz1-glib-2.78.0/include/glib-2.0/glib.h \
- display.h contain.h texts.h
diff --git a/display.o b/display.o
deleted file mode 100644
index c707579..0000000
Binary files a/display.o and /dev/null differ
diff --git a/hot.d b/hot.d
deleted file mode 100644
index c90269a..0000000
--- a/hot.d
+++ /dev/null
@@ -1 +0,0 @@
-hot.o: hot.c contain.h texts.h callback.h
diff --git a/hot.o b/hot.o
deleted file mode 100644
index 2bb792f..0000000
Binary files a/hot.o and /dev/null differ
diff --git a/in_depth.c b/in_depth.c
new file mode 100644
index 0000000..e6e6d53
--- /dev/null
+++ b/in_depth.c
@@ -0,0 +1,8 @@
+#include <gtk-4.0/gtk/gtk.h>
+#include <assert.h>
+
+static int run_edit_mode_val = 0;
+
+void set_run_edit_mode (int prescribed_mode) {run_edit_mode_val = prescribed_mode;}
+int  get_run_edit_mode () {return run_edit_mode_val;}
+
diff --git a/in_depth.h b/in_depth.h
new file mode 100644
index 0000000..a3f1cc8
--- /dev/null
+++ b/in_depth.h
@@ -0,0 +1,6 @@
+#include <gtk-4.0/gtk/gtk.h>
+#include <assert.h>
+
+void set_run_edit_mode (int prescribed_mode);
+int  get_run_edit_mode ();
+
diff --git a/main.c b/main.c
index 69beb76..eb1eb5c 100644
--- a/main.c
+++ b/main.c
@@ -15,7 +15,7 @@ int main (int argc, char **argv)
   int status;
 
   app = gtk_application_new ("org.jean.GTK4_GG_hack", G_APPLICATION_DEFAULT_FLAGS);
-  g_signal_connect (app, "activate", G_CALLBACK (activate), NULL);
+  g_signal_connect (app, "activate", G_CALLBACK (ui_main_window), NULL);
   status = g_application_run (G_APPLICATION (app), argc, argv);
   g_object_unref (app);
 
diff --git a/main.d b/main.d
deleted file mode 100644
index 6c89c45..0000000
--- a/main.d
+++ /dev/null
@@ -1 +0,0 @@
-main.o: main.c callback.h
diff --git a/main.o b/main.o
deleted file mode 100644
index 9d48ed0..0000000
Binary files a/main.o and /dev/null differ
diff --git a/myprogram b/myprogram
deleted file mode 100755
index c186e21..0000000
Binary files a/myprogram and /dev/null differ
diff --git a/texts.d b/texts.d
deleted file mode 100644
index 18de62c..0000000
--- a/texts.d
+++ /dev/null
@@ -1 +0,0 @@
-texts.o: texts.c
diff --git a/texts.o b/texts.o
deleted file mode 100644
index 8ea2834..0000000
Binary files a/texts.o and /dev/null differ
diff --git a/hot.c b/tree.c
similarity index 97%
rename from hot.c
rename to tree.c
index f7f257b..99c6fbb 100644
--- a/hot.c
+++ b/tree.c
@@ -12,11 +12,6 @@
 //  https://docs.gtk.org/gtk4/class.Widget.html#height-for-width-geometry-management
 //  GTK_ORIENTATION_VERTICAL       GTK_ORIENTATION_HORIZONTAL
 
-static int run_edit_mode_val = 0;
-
-void set_run_edit_mode(int prescribed_mode) {run_edit_mode_val = prescribed_mode;}
-int  get_run_edit_mode () {return run_edit_mode_val;}
-
 struct TreeNode_t {gchar *text; struct TreeNode_t *child, *next;};
 
 static void add_child_node (struct TreeNode_t *parent, struct TreeNode_t *child){
diff --git a/hot.h b/tree.h
similarity index 100%
rename from hot.h
rename to tree.h