diff --git a/include/base.h b/include/base.h
index 5f3bbe4..744aa22 100644
--- a/include/base.h
+++ b/include/base.h
@@ -36,7 +36,7 @@
 #include <math.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <string.h>
+#include <stddef.h> /* Defines NULL. */
 #include <stdbool.h>
 #include <sys/types.h>
 #include <sys/stat.h>
diff --git a/include/widget.h b/include/widget.h
index 2a61694..c971f47 100644
--- a/include/widget.h
+++ b/include/widget.h
@@ -86,21 +86,6 @@ int widget_get_object_transparency (int i);                            //  top
 /******************************************************************************/
 //                     called in : src/widget/rules/distrib.c
 
-// Define a structure for the stack
-#define MAX_SIZE 255
-typedef struct { GtkWidget *arr[MAX_SIZE]; int top; } Stack;
-
-Stack get_stack();
-void set_stack (Stack *stack_new);
-
-void initialize(Stack *stack);
-bool isEmpty(Stack *stack);
-bool isFull(Stack *stack);
-void push(Stack *stack, GtkWidget *value);
-GtkWidget *pop(Stack *stack);
-GtkWidget *peek(Stack *stack);
-void *push_images_onto_stack();
-
 void *widget_get_selected_rule();
 void *widget_get_rules_left_pane();
 void *widget_get_rules_page();
diff --git a/src/widget/rules/tree_tools/compare.c b/src/widget/rules/tree_tools/compare.c
index e68e6c5..a0cb673 100644
--- a/src/widget/rules/tree_tools/compare.c
+++ b/src/widget/rules/tree_tools/compare.c
@@ -33,57 +33,60 @@
 
 #define W_IMAGE_ABSURD 1920 / 32   //   1920 x 960    ad hoc  (pour mon écran)
 #define H_IMAGE_ABSURD 960
+#define MAX_SIZE 255
 
-Stack stack;
-
-Stack get_stack() {return stack;}
-void set_stack (Stack *stack_new) {stack = *stack_new;}
-
-//  https://www.geeksforgeeks.org/implement-stack-in-c/
-
-void *get_an_impression_of_what_a_rules_comparator_could_be(){
-
-    GtkBox *compare_left = GTK_BOX (gtk_box_new (GTK_ORIENTATION_VERTICAL, 2));
-    gtk_widget_set_size_request (GTK_WIDGET (compare_left), W_IMAGE_ABSURD, H_IMAGE_ABSURD);
-
-    GtkBox *compare_right = GTK_BOX (gtk_box_new (GTK_ORIENTATION_VERTICAL, 2));
-    gtk_widget_set_size_request (GTK_WIDGET (compare_right), W_IMAGE_ABSURD, H_IMAGE_ABSURD);
-
-    initialize(&stack);
-
-    push_images_onto_stack (stack);
-
-    push(&stack, GTK_WIDGET (gtk_picture_new_for_filename
-        ("/home/jean/Gem-Graph/gem-graph-client/data/image/ATP.png")));
-    push(&stack, GTK_WIDGET (gtk_picture_new_for_filename
-        ("/home/jean/Gem-Graph/gem-graph-client/data/image/ADP.png")));
-    push(&stack, GTK_WIDGET (gtk_picture_new_for_filename
-        ("/home/jean/Gem-Graph/gem-graph-client/data/image/AMP.png")));
-
-    gtk_box_append (compare_left, pop(&stack));
-    gtk_box_append (compare_left, pop(&stack));
-    gtk_box_append (compare_left, pop(&stack));
-//    gtk_box_append (compare_left, pop(&stack));
-
-    GtkBox *comparator = GTK_BOX (gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 2));
-    gtk_box_append (comparator, GTK_WIDGET (compare_left));
-    gtk_box_append (comparator, GTK_WIDGET (compare_right));
-
-    return comparator;
+// -----------------------------------------------------------------------
+// Below is ^c^v from  RMS C manual
+//
+struct intlistlink {int datum; struct intlistlink *next;} babar;
+struct intlistlink *my_list = NULL;
+struct intlistlink *alloc_intlistlink ()
+{
+    struct intlistlink *p;
+    p = malloc (sizeof (struct intlistlink));
+    if (p == NULL) printf ("fatal: ran out of storage");
+    p->datum = 0;
+    p->next = NULL;
+    return p;
 }
+void add_to_mylist (int my_int)
+{
+    struct intlistlink *p = alloc_intlistlink ();
+    p->datum = my_int;
+    p->next = my_list;
+    my_list = p;
+}
+void free_intlist (struct intlistlink *p)
+{
+    while (p)
+    {
+        struct intlistlink *q = p;
+        p = p->next;
+        free (q);
+    }
+}
+// TODO free_intlist (mylist);
+// TODO mylist = NULL;
+// TODO offsetof (type, field)
+//
+//
+// -----------------------------------------------------------------------
+// Below is ^c^v from  https://www.geeksforgeeks.org/implement-stack-in-c/
 
-void initialize (Stack *stack) { stack->top = -1; }
-bool isEmpty (Stack *stack) { return stack->top == -1; }
-bool isFull (Stack *stack) { return stack->top == MAX_SIZE - 1; }
+typedef struct { GtkWidget *arr[MAX_SIZE]; int top; } Stack;
+static Stack stack_b;
+static void initialize (Stack *stack) { stack->top = -1; }
+static bool isEmpty (Stack *stack) { return stack->top == -1; }
+static bool isFull (Stack *stack) { return stack->top == MAX_SIZE - 1; }
 
-void push (Stack *stack, GtkWidget *value)
+static void push (Stack *stack, GtkWidget *value)
 {
     if (isFull(stack)) { printf("Stack Overflow\n"); return; }
     stack->arr[++stack->top] = value;
     printf("%d  ", stack->top);
 }
 
-GtkWidget *pop (Stack *stack)
+static GtkWidget *pop (Stack *stack)
 {
     if (isEmpty(stack)) { printf("Stack Underflow\n"); return NULL; }
     GtkWidget *popped = stack->arr[stack->top];
@@ -93,12 +96,52 @@ GtkWidget *pop (Stack *stack)
     return popped;
 }
 
-GtkWidget *peek(Stack *stack)
+static GtkWidget *peek(Stack *stack)
 {
     if (isEmpty(stack)) { printf("Stack is empty\n"); return NULL; }
     return stack->arr[stack->top];
 }
 
+// -----------------------------------------------------------
+// confrontation of both examples and methods
+
+static void *push_images_onto_stack (Stack stack_b);
+
+void *get_an_impression_of_what_a_rules_comparator_could_be(){
+
+    GtkBox *compare_left = GTK_BOX (gtk_box_new (GTK_ORIENTATION_VERTICAL, 2));
+    gtk_widget_set_size_request (GTK_WIDGET (compare_left), W_IMAGE_ABSURD, H_IMAGE_ABSURD);
+
+    GtkBox *compare_right = GTK_BOX (gtk_box_new (GTK_ORIENTATION_VERTICAL, 2));
+    gtk_widget_set_size_request (GTK_WIDGET (compare_right), W_IMAGE_ABSURD, H_IMAGE_ABSURD);
+
+    initialize(&stack_b);
+
+    push_images_onto_stack (stack_b);
+
+    push(&stack_b, GTK_WIDGET (gtk_picture_new_for_filename
+        ("/home/jean/Gem-Graph/gem-graph-client/data/image/ATP.png")));
+    push(&stack_b, GTK_WIDGET (gtk_picture_new_for_filename
+        ("/home/jean/Gem-Graph/gem-graph-client/data/image/ADP.png")));
+    push(&stack_b, GTK_WIDGET (gtk_picture_new_for_filename
+        ("/home/jean/Gem-Graph/gem-graph-client/data/image/AMP.png")));
+
+    printf(" ---------   \n");//%d\n", *stack_b->arr[0]);
+
+    peek(&stack_b);
+//    gtk_box_append (compare_left, peek(&stack_b));
+    gtk_box_append (compare_left, pop(&stack_b));
+    gtk_box_append (compare_left, pop(&stack_b));
+    gtk_box_append (compare_left, pop(&stack_b));
+//    gtk_box_append (compare_left, pop(&stack));
+
+    GtkBox *comparator = GTK_BOX (gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 2));
+    gtk_box_append (comparator, GTK_WIDGET (compare_left));
+    gtk_box_append (comparator, GTK_WIDGET (compare_right));
+
+    return comparator;
+}
+
 
 
 
@@ -114,7 +157,7 @@ GtkWidget *peek(Stack *stack)
 
 
 
-void *push_images_onto_stack (Stack stack)
+static void *push_images_onto_stack (Stack stack)
 {
     clock_t start, end;
     printf("compare.c push_images_onto_stack() start  >>  ");