Just bought this game and so far I love it, but I would love to be able to play in windowed mode. I also got screwed into a lower resolution.
On first load the relevant graphics settings were:
resolution: 1920 x 1080
I unchecked the fullscreen box and clicked apply, but nothing happened. I closed the settings, clicked "Save" when prompted, but still nothing. I restarted the game and I was still in fullscreen. I repeated this several times with the exact same results. When I uncheck fullscreen it remains checked until I leave that page, but when I return it is checked.
Next I tried changing the resolution. I opened the dropdown and there were only two options, 1440 x 900 and 1280 x 800. I selected 1440 x 900, unchecked fullscreen, and applied. The resolution was set correctly, but still no fullscreen. Exited, settings and clicked save, fullscreen. Restarted, fullscreen again.
I reopened the game and tried to set my resolution back to 1920 x 1080, but it was not an available option. I changed to the smaller resolution and repeated the same process as above without fullscreen. I changed back to 1440 x 900 successfully, but still not windowed mode and still no 1920 x 1080.
I reloaded the game a few more times but made no progress. The resolution isn't as big of a deal as the windowed mode for me.
I bought the game through GOG and installed using their Galaxy Client.
OSX Yosemite 10.10.4 (14E46)
MacBook Pro (Retina, 15-inch, Mid 2015)
2.8 GHz Intel Core i7
16 GB 1600 MHz DDR3
AMD Radeon R9 M370X 2048 MB
15.4-inch (2880 x 1800)