Extra argument to grid_block to generate grid class.

I'm just using fusion theme for the first time and I noticed a theme function called grid_block. I figured out what it did and I was thinking that it would be cool if you could add another argument that would give the outputted html a grid class. For example this snippet would give the markup a class of grid16-4:
<?php print theme('grid_block', $search_box, 'search-box', 4); ?>

Just an idea. I added a basic patch.