diff --git a/Makefile b/Makefile
index 35a3fe1..7e718ca 100644
--- a/Makefile
+++ b/Makefile
@@ -15,22 +15,64 @@ OPTIMIZE = -O2
 all:
 	exec
 
-exec.o:
-	$(CC) $(CFLAGS) $(WARNINGS) $(DEBUG) $(OPTIMIZE) warm.c -o $@ main.c
+exec.o: hot.c warm.c cold.c main.c Makefile
+	$(CC) $(CFLAGS) $(WARNINGS) $(DEBUG) $(OPTIMIZE) hot.c warm.c cold.c -o $@ main.c
 
 clean:
 	rm -f exec.o
 
+# Builder will call this to install the application before running.
 install:
 	echo "Installing is not supported"
 
-run:
+# Builder uses this target to run your application.
+run: exec.o
 	./exec.o
 
 
 
 
 
+
+
+
+
+#------------------------------------------------------------------------------#
+#             To study : can the following commands be removed ?               #
+#------------------------------------------------------------------------------#
+
+#SHELL = /bin/sh
+#.SUFFIXES:
+#.SUFFIXES: .c .o .h       # is  .h  useful ?
+#.PHONY = run
+#.PHONY = clean
+#.PHONY: Makefile
+
+#CC=gcc
+#CFLAGS=`pkg-config --cflags gtk4 --libs gtk4`
+#WARNINGS = -Wall
+#DEBUG = -ggdb -fno-omit-frame-pointer
+#OPTIMIZE = -O2
+
+# in exec.o:
+#	$(CC)  $(CFLAGS) $(WARNINGS) $(DEBUG) $(OPTIMIZE)
+#	après les $(...), dans : warm.c -o $@ main.c  le $@  peut être supprimé
+#all:
+#	exec
+
+#install:
+#	echo "Installing is not supported"
+
+
+
+
+
+
+#------------------------------------------------------------------------------#
+#                        Personnal notes & links                               #
+#------------------------------------------------------------------------------#
+
+
 # gcc $( pkg-config --cflags gtk4 ) -o exec main.c $( pkg-config --libs gtk4 )
 
 #       https://www.gnu.org/software/make/manual/
diff --git a/cold.c b/cold.c
new file mode 100644
index 0000000..79e887e
--- /dev/null
+++ b/cold.c
@@ -0,0 +1,4 @@
+#include <stdio.h>
+#include <gtk-4.0/gtk/gtk.h>
+
+void print_text(GtkWidget *widget, gpointer data) {g_print (data);}
diff --git a/cold.h b/cold.h
new file mode 100644
index 0000000..bae6424
--- /dev/null
+++ b/cold.h
@@ -0,0 +1,14 @@
+#include <stdio.h>
+#include <gtk/gtk.h>
+
+void print_text(GtkWidget *widget, gpointer data);
+/*
+  GtkWidget *button_0 = gtk_button_new_with_label ("Quit");
+  GtkWidget *button_1 = gtk_button_new_with_label ("I");
+  GtkWidget *button_2 = gtk_button_new_with_label ("II");
+  GtkWidget *button_3 = gtk_button_new_with_label ("III");
+  GtkWidget *button_4 = gtk_button_new_with_label ("IV");
+  GtkWidget *button_5 = gtk_button_new_with_label ("V");
+*/
+//  GtkToggleButton *tb1 =  GTK_TOGGLE_BUTTON (gtk_button_new_with_label ("tb1"));
+
diff --git a/exec.o b/exec.o
index b9b918b..9a622b7 100755
Binary files a/exec.o and b/exec.o differ
diff --git a/hot.c b/hot.c
new file mode 100644
index 0000000..b7f0285
--- /dev/null
+++ b/hot.c
@@ -0,0 +1,4 @@
+#include <stdio.h>
+#include <gtk-4.0/gtk/gtk.h>
+
+
diff --git a/hot.h b/hot.h
new file mode 100644
index 0000000..ee69459
--- /dev/null
+++ b/hot.h
@@ -0,0 +1,3 @@
+#include <stdio.h>
+#include <gtk-4.0/gtk/gtk.h>
+
diff --git a/main.c b/main.c
index b05e542..cf5c551 100755
--- a/main.c
+++ b/main.c
@@ -1,5 +1,7 @@
 #include <gtk/gtk.h>
+#include "hot.h"
 #include "warm.h"
+#include "cold.h"
 
 static void activate (GtkApplication *app, gpointer user_data) {
   GtkWidget *button_0 = gtk_button_new_with_label ("Quit");
diff --git a/warm.c b/warm.c
index 0f22fe4..4debdbb 100644
--- a/warm.c
+++ b/warm.c
@@ -12,4 +12,4 @@
 
 //  GtkToggleButton *tb1 =  GTK_TOGGLE_BUTTON (gtk_button_new_with_label ("tb1"));
 
-void print_text(GtkWidget *widget, gpointer data) {g_print (data);}
+
diff --git a/warm.h b/warm.h
index 2a944d3..6a820f8 100644
--- a/warm.h
+++ b/warm.h
@@ -13,6 +13,7 @@
 #include <glib-2.0/glib.h>
 #include <gtk-4.0/gtk/gtk.h>
 
+/*
 extern GtkWidget *button_0;
 extern GtkWidget *button_1;
 extern GtkWidget *button_2;
@@ -21,4 +22,4 @@ extern GtkWidget *button_4;
 extern GtkWidget *button_5;
 
 void print_text(char *text);
-
+*/