I was getting a bit frustrated about fixing the vertical lines problem. I can get pretty "anal" when I want something to look good. At one point I just let it all go and decided to finish the last few commands that needed to be implemented. When all that was done, to my surprise there was a bonus challenge... to make the rendering engine look exactly like what I've been trying to do. Since I had 90% of the logic down, I just followed through with the solution.
Now for some more theory!
