diff --git a/src/graphics/graphics.c b/src/graphics/graphics.c
index 1098b4b..32702f1 100644
--- a/src/graphics/graphics.c
+++ b/src/graphics/graphics.c
@@ -70,7 +70,7 @@ static void show_user_choices(GLuint *arrows, int arrows_nb,
 
 static void get_model_data_and_user_preferences(GLuint *arrows, int arrows_nb)
 {
-    xxx = 8;    //   0 < model_space_size_x
+    xxx = 1;    //   0 < model_space_size_x
     yyy = 1;    //   0 < model_space_size_y
     zzz = 1;    //   0 < model_space_size_z
     pref_show_grids = 0;    //  0,   1,   2, 3, 5,   6, 10, 15,   30,   etc
@@ -158,7 +158,7 @@ static bool erase_arrow (GLuint *arrows, int arrows_nb, int address, int site, i
         *(arrows + address + 4) = *(arrows + arrows_nb * 5 + 4);
     }
     buffer_lines_size -= (3 + 4) * 2;
-    buffer_lines_origin = g_realloc(buffer_lines_origin, buffer_lines_size * 2 * sizeof(GLuint));
+    buffer_lines_origin = g_realloc(buffer_lines_origin, buffer_lines_size * sizeof(GLuint));
 
     show_arrows_array(arrows, arrows_nb, address, -1, 0, site, x, y, z);
 
@@ -188,11 +188,11 @@ static void show_arrows_array (GLuint *arrows, int arrows_nb, int address, int c
         printf("   [%4d] =  %2d  | %2d,  %2d,  %2d,  %2d    ",\
                i, *(arrows + i * 5 + 0), *(arrows + i * 5 + 1), *(arrows + i * 5 + 2),\
                *(arrows + i * 5 + 3), *(arrows + i * 5 + 4));
-        if (weight == 0 && i == address / 5) printf(" <<<|   < - > (%d, %d, %d, %d)   @ [%d]",\
+        if (weight == 0 && i == address / 5) printf(" <<<|   < - > (%d, %d, %d, %d)   moved at [%2d]",\
                *(arrows + i * 5 + 1), *(arrows + i * 5 + 2),\
                *(arrows + i * 5 + 3), *(arrows + i * 5 + 4), address / 5);
         if (weight > 0 && current_weigh != weight && i == arrows_nb - 1 && address >= 0)
-            printf(" <<<    < + > (%d, %d, %d, %d)   @ [%d]",\
+            printf(" <<<    < + > (%d, %d, %d, %d)   added at [%2d]",\
                *(arrows + i * 5 + 1), *(arrows + i * 5 + 2),\
                *(arrows + i * 5 + 3), *(arrows + i * 5 + 4), address / 5);
         if (weight > 0 && current_weigh == weight && i == address / 5) printf("    <");
@@ -827,17 +827,18 @@ void main_test_graphics (void)
 
     GLuint arrows[] = {
           1,    0,    0, 0, 0,
-//          1,    1,    0, 0, 0,
+          1,    1,    0, 0, 0,
 //          1,    1,    0, 0, 0,
 //          1,    0,    2, 0, 0,
-          1,    1,    1, 0, 0,
-          1,    1,    2, 0, 0,
-          1,    1,    3, 0, 0,
-          1,    1,    4, 0, 0,
-          1,    1,    5, 0, 0,
-          1,    1,    6, 0, 0,
-          1,    1,    7, 0, 0,
-          1,    0,    7, 0, 0,
+          /* 1,    1,    1, 0, 0, */
+          /* 1,    1,    2, 0, 0, */
+          /* 1,    1,    3, 0, 0, */
+          /* 1,    0,    4, 0, 0, */
+          /* 1,    1,    4, 0, 0, */
+          /* 1,    1,    5, 0, 0, */
+          /* 1,    1,    6, 0, 0, */
+          /* 1,    1,    7, 0, 0, */
+          /* 1,    0,    7, 0, 0, */
 //          1,    2,    0, 0, 0,
 //          1,    3,    0, 0, 0,
 //          1,    4,    0, 0, 0,
@@ -874,7 +875,7 @@ void main_test_graphics (void)
 //    set_arrow (arrows, arrows_nb, 0, 1, 1, 0, 0); arrows_nb = sizeof(arrows) / sizeof(arrows[0]) / 5;   //  arrows_nb --;
 //    set_arrow (arrows, arrows_nb, 0, 1, 0, 0, 0); arrows_nb = sizeof(arrows) / sizeof(arrows[0]) / 5;   //  arrows_nb --;
 
-//    set_arrow (arrows, arrows_nb, 1, 0, 1, 0, 0); arrows_nb = sizeof(arrows) / sizeof(arrows[0]) / 5;   //  arrows_nb ++;
+//    set_arrow (arrows, arrows_nb, 1, 0, 5, 0, 0); arrows_nb = sizeof(arrows) / sizeof(arrows[0]) / 5;   //  arrows_nb ++;
 //    set_arrow (arrows, arrows_nb, 1, 1, 1, 0, 0); arrows_nb = sizeof(arrows) / sizeof(arrows[0]) / 5;   //  arrows_nb ++;
 //    set_arrow (arrows, arrows_nb, 1, 0, 0, 0, 0); arrows_nb = sizeof(arrows) / sizeof(arrows[0]) / 5;   //  arrows_nb ++;
 
@@ -899,18 +900,17 @@ void main_test_graphics (void)
 
     int offset_after_arrows = buffer_vertex_size / 3, difference = offset_after_arrows - offset_after_grids;
 
-    if (1) printf("\nbuffer_vertex_offset_after grids = %d\t\t(x+1)*(y+1)*(z+1) = %d  (x,y,z = %d,%d,%d)",\
+    if (1) printf("\n    buffer_vertex_offset_after grids = %6d\t%6d = (x+1)*(y+1)*(z+1);  <-->  (x,y,z = %d,%d,%d)",\
                   offset_after_grids,  (xxx + 1)*(yyy + 1)*(zzz + 1), xxx, yyy, zzz);
-    if (1) printf("\nbuffer_vertex_offset_after arrows = %d\t\t(%d - %d = %d,    %d / 12 <> %d cubes)",\
+    if (1) printf("\n   buffer_vertex_offset_after arrows = %6d\t%6d = %d + %d;  <-->  %d = 12 x %d  (there are %d cubes)",\
                   offset_after_arrows, offset_after_arrows, offset_after_grids,\
-                  difference, difference, difference / 12);
-    if (1) printf("\nbuffer_lines_size after cubes = %d\t\t(%d x %d  +  %d x %d  +  %d x %d = %d) (x 2 = %d)",\
-                  buffer_lines_size_after_cubes, xxx+1, yyy+1, xxx+1, zzz+1, yyy+1, zzz+1,\
-                  (xxx+1) * (yyy+1) + (xxx+1) * (zzz+1) + (yyy+1) * (zzz+1),\
-                  ((xxx+1) * (yyy+1) + (xxx+1) * (zzz+1) + (yyy+1) * (zzz+1)) * 2);
-    if (1) printf("\nbuffer_lines_size after arrows = %d\t\t(%d - %d = %d;\t(3 + 4) x %d = %d  (x 2 = %d)\n", buffer_lines_size,\
+                  difference, difference, difference / 12, difference / 12);
+    if (1) printf("\n     buffer_lines_offset after cubes = %6d\t%6d = 2 * (%dx%d + %dx%d + %dx%d);  <-->  2 * (x*y + x*z + y*z)",\
+                  buffer_lines_size_after_cubes, ((xxx+1) * (yyy+1) + (xxx+1) * (zzz+1) + (yyy+1) * (zzz+1)) * 2,
+                  xxx+1, yyy+1, xxx+1, zzz+1, yyy+1, zzz+1);
+    if (1) printf("\n    buffer_lines_offset after arrows = %6d\t%6d = %d + %d;  <-->  %d = (3 + 4) x 2 x %d  (arrows_nb = %d)\n", buffer_lines_size,\
                   buffer_lines_size, buffer_lines_size_after_cubes, buffer_lines_size - buffer_lines_size_after_cubes,\
-                  arrows_nb, arrows_nb * 7, arrows_nb * 14);
+                  arrows_nb * 14, arrows_nb, arrows_nb);
 
     if (0) printf("main_test_graphics [ok]\n");
 }