It would be nice if I could pass NULL for sibling in gtk_grid_attach_next_to, meaning attach at the beginning or end of the current contents. This isn't perfectly defined. As if you specify e.g. BOTTOM you don't know which column is meant. However, if we just assume the first column you would be fine.

Having this means you can e.g. do:

GtkWidget *last = NULL;

for (i = 0; i < LEN; i++) {
   child = ...
   gtk_grid_attach_next_to (grid, child, last, GTK_POS_BOTTOM,
                            CHILD_WIDTH, CHILD_HEIGHT);
   ...
   last = child;
}

You can do a similar loop just with gtk_container_add, but then you can't specify
the span of the child.