Added "Working through Screens"

free-programming-books.md

@@ -186,6 +186,7 @@
 * [Best of Smashing Magazine](http://anniversary.smashingmagazine.com/best-of-smashing-magazine.zip)
 * [Programming with gtkmm 3](https://developer.gnome.org/gtkmm-tutorial/stable/)
 * [Search User Interfaces](http://searchuserinterfaces.com/book/) - Marti A. Hearst
+* [Working through Screens](http://www.flashbulbinteraction.com/WTS.html) - Jacob Burghardt
 
 
 ###Language Agnostic