tommcfarlin/WordPress-Plugin-Boilerplate — pull request #142 by jrivera84 (2013-12-10 18:40:32+00:00)
Title: Depreciated Function

Screen Icon function has been depreciated and CSS output is hidden in MP6.
http://core.trac.wordpress.org/ticket/26119

screen_icon no longer returns anything as of WP 3.8: http://core.trac.wordpress.org/changeset/26537