My Hardware: Macbook Air, Yosemite; Arduino 1.6.2
For the last while, my IDE seems to revert back to this, as pictured. I tried changing things in the preferences.txt file (while Arduino was closed). I tried just deleting that file. I even just upgraded to the latest 1.6.2
For a while, it will open sketches in the same size as when I last closed them, but then after a few times they open up tiny again. I don’t know why.