diff --git a/src/graphics/graphics.c b/src/graphics/graphics.c
index 8a354bd..57291a9 100644
--- a/src/graphics/graphics.c
+++ b/src/graphics/graphics.c
@@ -488,9 +488,8 @@ static void show_user_choices(GLuint *arrows, int arrows_nb,
 static void show_user_action(GLuint *arrows, int arrows_nb, int address, int requested_weight,
                              int current_weight, int site, int x, int y, int z)
 {
-    if (address == -1 && requested_weight  > 0) {printf("no such arrow found (%d,%d,%d,%d)\n\
-                                                  requested weight == %d  =>  CREATE",\
-        arrows[address + 1], arrows[address + 2], arrows[address + 3], arrows[address + 4], requested_weight); return;}
+    if (address == -1 && requested_weight  > 0) {printf("no such arrow found (address == -1)\n\
+                                                  requested weight == %d  =>  CREATE", requested_weight); return;}
 
     if (address >=  0 && requested_weight == 0) {printf("arrow (%d,%d,%d,%d) found at address %d;  current_weight = %d;\n\
                                                   requested weight == %d  =>  ERASE",\
@@ -500,14 +499,12 @@ static void show_user_action(GLuint *arrows, int arrows_nb, int address, int req
                                                   requested weight != current weight  =>  MODIFY",\
         arrows[address + 1], arrows[address + 2], arrows[address + 3], arrows[address + 4], address/5, current_weight); return;}
 
-    if (address >=  0 && current_weight == requested_weight){
-        printf("arrow (%d,%d,%d,%d) found at address %d;\n\
+    if (address >=  0 && current_weight == requested_weight){printf("arrow (%d,%d,%d,%d) found at address %d;\n\
                                                   requested_weight == current_weight  =>  END",\
         arrows[address + 1], arrows[address + 2], arrows[address + 3], arrows[address + 4], address/5); return;}
 
-    if (address == -1 && requested_weight == 0) {printf("no such arrow found (%d,%d,%d,%d)\n\
-                                                  requested weight == 0  =>  END",\
-        arrows[address + 1], arrows[address + 2], arrows[address + 3], arrows[address + 4]); return;}
+    if (address == -1 && requested_weight == 0) {printf("no such arrow found (address == -1)\n\
+                                                  requested weight == 0  =>  END"); return;}
 }
 
 /*
@@ -558,7 +555,9 @@ static int rewrite_arrow (GLuint *arrows, int arrows_nb, int address, int weight
 */
 static int create_arrow (GLuint *arrows, int arrows_nb, int weight, int site, int x, int y, int z)
 {
-    buffer_lines_origin = g_realloc(buffer_lines_origin, buffer_lines_size * sizeof(GLuint));
+//    buffer_lines_size += 14;
+
+    buffer_lines_origin = g_realloc(buffer_lines_origin, buffer_lines_size * 2 * sizeof(GLuint));
 
     assert (buffer_lines_origin); assert (buffer_lines_size);
 
@@ -657,14 +656,14 @@ void main_test_graphics (void)
 //  assert : no more than one arrow per address           TODO   NOT checked before init
 //  notify : weights are replaced, NOT added (could be !) TODO
 
-    int space_X = 4,    space_Y = 1,     space_Z = 1;
+    int space_X = 3,    space_Y = 3,     space_Z = 3;
     int pref_show_grids = 0;    //  0,   1,   2, 3, 5,   6, 10, 15,   30,   etc
                                 // xyz,  0,   x, y, z,  xy, xz, yz,  xyz
     GLuint arrows[] = {
           1,    0,    0, 0, 0,
           1,    1,    1, 0, 0,
-          1,    0,    2, 0, 0,
-          1,    1,    3, 0, 0,
+          1,    2,    2, 0, 0,
+          1,    3,    0, 2, 0,
     //  load, site,   x, y, z
     };
     int arrows_nb = sizeof(arrows) / sizeof(arrows[0]) / 5;
@@ -683,10 +682,11 @@ void main_test_graphics (void)
      *           are always defined (whether arrows are drawn or not). */
     arrows_write_terminations (space_X, space_Y, space_Z);
 
-    arrows_nb = set_arrow (arrows, arrows_nb, 0, 0, 0, 0, 0);
     arrows_nb = set_arrow (arrows, arrows_nb, 0, 0, 2, 0, 0);
     arrows_nb = set_arrow (arrows, arrows_nb, 0, 1, 1, 0, 0);
     arrows_nb = set_arrow (arrows, arrows_nb, 0, 1, 3, 0, 0);
+    arrows_nb = set_arrow (arrows, arrows_nb, 1, 1, 2, 2, 0);
+    arrows_nb = set_arrow (arrows, arrows_nb, 1, 3, 0, 2, 0);
 
     int weight = 0, site = 0,
         stx = space_Z * space_Y, sty = space_Z, stz = 1, arrow_offset = 0;
diff --git a/src/graphics/shaders_study.c b/src/graphics/shaders_study.c
index c86d60d..3608370 100644
--- a/src/graphics/shaders_study.c
+++ b/src/graphics/shaders_study.c
@@ -31,21 +31,16 @@
 #define VERTEX_SHADER_FILE "src/shaders/shader.vert"
 #define FRAG_SHADER_FILE "src/shaders/shader.frag"
 
+
 //  Que fait l'instruction suivante (ligne 397 de graphics.c)
 //     dans  "bool graphics_init(const char *gl_area)" ?
 //
 //    if (!graphics_init_shaders(gl_area)) return false;
-
-
-static volatile int buffer_vertex_size = 0;
-static volatile int buffer_lines_size = 0;
-static volatile int buffer_colors_size = 0;
-static volatile int buffer_plans_size = 0;
-
-/*
- * Dynamic array of ptrs to dynamically allocated gl_area_entry
- */
-//  struct gl_area_entry **gl_area_array = NULL;
+//
+//  Et comment et pourquoi cette structure "gl_area_array" ?
+// (Dynamic array of ptrs to dynamically allocated gl_area_entry)
+//
+//      struct gl_area_entry **gl_area_array = NULL;