layout(&env, start_block, opts->x_margin);
set_y(&env, start_block, opts->y_margin);
start_dims = pmap_get(env.block_dims, start_block);
layout(&env, start_block, opts->x_margin);
set_y(&env, start_block, opts->y_margin);
start_dims = pmap_get(env.block_dims, start_block);