When porting a theme from 4.7 and moving to a different server, I had to repair paths to images in the theme directory that were hard-coded into the tpl files.
With this patch, instead of:
<?php base_path() . path_to_theme() ?>/box_bottom.png
I can include, more succinctly:
<?php base_path_to_theme() ?>/box_bottom.png
These paths won't break when the theme is moved around in the sites directory or renamed.