background style - not ready to merge

Hi all,

This is my next installment of addressing #711.

This branch works as expected and is almost ready to go in . . . except for a broken spec. (Comments in-line) Has to do with resource disposal . . . perhaps @jasonrclark can help? :)
You probably can not comment there because no line was changed there. 

It seems like dispose behavior was broken for some reason (GLAD we have those tests!). Have a look at the defined dispose method.. it seems like the fill color of the gui does not get disposed properly now perhaps because we store it differently now and it is not added to the list of things to be disposed.