Kerbal Space Program

This may be similar to #6017 http://bugs.kerbalspaceprogram.com/issues/6017

If I run in windowed mode and set the resolution to be my native (1920x1200) then other settings won't get saved and the accept and apply buttons seen not to do anything.

First (expected behaviour) I start the game and set a resolution less than my native res. If press accept I am returned to the main menu. If I then return to settings and change a different setting (render quality for example) and press accept then the setting is saved and I return to the main menu. If at that point I close the game and restart and then go back into settings the render quality I set is still as I set it.
Now if I go into settings and set my native res of 1920x1200 when I press accept as before I am returned to the main menu and the resolution is set. If I go back into settings it still says 1920x1200. (still as expected).

But if I restart the game and go back into settings the resolution does not say 1920x1200, it says custom. Also neither accept or apply do anything, the only way back to the main menu is to press cancel. But if I change a setting (sometime obvious like orbit line strength) and press apply and then cancel when I go into the game that setting has been set. However when I restart the game that setting is lost. The workaround is to change the resolution from custom back to 1920x1200 at the same time as making other settings changes, then accept/apply function as expected and the setting is properly saved (ie persists over a restart).

I don't know of this is due to the res being set to 1920x1200 specifically, or if it's caused by running in windowed mode at natives res.
Steps to repeat
- launch game and go into settings, set a res of 1920x1200 (assuming that's native)
- click accept.
- restart the game and go back into settings (note that it now says custom for resolution).
- change a different setting ie terrain detail or render quality (and of the ones on the left).
- click apply or accept and note that neither button functions.
- click cancel and go into game - the settings should appear to have been changed.
- restart the game and go back into settings, note that the settings have been reverted.
- again change one of the ones of the left but this time also change the resolution from custom back to 1920x1200
- now accept will function as expected.
- restart game and note that settings have been preserved.

The workaround is making sure to change resolution from custom to desired res (even though "custom" is the desired res) in order for other graphics settings to be saved.

The settings file attached is when the res set to 1920x1200 and when I load up on that .cfg it displays custom and neither accept or apply appear to do anything.
dxdiag - https://www.dropbox.com/s/4v2eco8060wfx6c/DxDiag.txt?dl=0