Alright. I have a bit of a problem.
I'm on a new Macbook Air, less than 2 months old. Currently running OS X 10.11 El Capitan.
It has a maximum resolution of 2560x1600.
The screen's width is 13 inches.
I set my resolution to 2560x1600, and forgot to tick fullscreen.
Now the drop-down box to set resolution is out of my reach, as I cannot move the Spiral Knights window any more up than it is. Resetting the game only furthers my problem.

Uninstalling and reinstalling did nothing.

I peeked around in /rsrc/config, which was filled with .dat files I cannot and will not open.

I have a feeling that I need to completely delete the Spiral Knights folder in steamapps/common.
Any other ways to change the resolution from outside of the game?

Edit: Completely deleting the folder in steamapps/common did nothing. After uninstalling it via Steam. I am thoroughly stuck.