How to add customize resolution setting to setting page options?

[royying]

I have set the KSP resolution to 1900 x 1000 by edit the setings.cfg, to make a biggest window screen,

but if I change the settings in game setting page,the resolution will auto change to 800 X 600,

I think the reason is the current resolution don't match the resolution options,

so I want to add some new options for game resolution,

can anyone teach me how to do it?THANKS~