`draw_shadows` effects the shadow cast by the Sublime "minimap" -- the code shape outline on the right side of the window.

You can see the effect of turning it off by comparing the right sides of the single pair of (before/after) screenshots in the article.

before: http://thume.ca/assets/postassets/sublimesecrets/debug_rende...

after: http://thume.ca/assets/postassets/sublimesecrets/configs.png

You need a file with a line longer than your window is wide. Then whichever side(s) of your window have content scrolled off the side of them will have a slight shadow effect on them. It's actually quite cool and I think indicative of the kind of polish present in Sublime but not other editors. But I can see some finding it annoying in some circumstances.

Also, after discovering this I Googled it and saw that some other people mentioning it (no hits for the other settings) in connection to the Soda theme, so maybe if you are using that it might already be disabled? I'm not sure.