box = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 0);
gtk_box_pack_start (GTK_BOX (box), gtk_label_new ("One"), FALSE, FALSE, 0);
gtk_box_pack_start (GTK_BOX (box), gtk_label_new ("Two"), FALSE, FALSE, 0);
This can be done with GtkGrid as follows:
grid = gtk_grid_new ();
child1 = gtk_label_new ("One");
gtk_grid_attach (GTK_GRID (grid), child1, 0, 0, 1, 1);
child2 = gtk_label_new ("Two");
gtk_grid_attach_next_to (GTK_GRID (grid), child2, child1, GTK_POS_RIGHT, 1, 1);
And similarly for gtk_box_pack_end(). In that case, you
would use GTK_POS_LEFT to place the grid children from
left to right.
If you only need to pack children from the start, using
gtk_container_add() is an even simpler alternative. GtkGrid
places children added with gtk_container_add() in a single
row or column according to its “orientation”.