Window
Window Size allows you to select one of four standard window sizes, or a custom size.
Window Colors allows you to set the number of windows colors to 16 or 256.
256 Color Mapping allows you to set up 256 color sessions to use approximate or exact colors. Use Approximate Colors to eliminate color flashing when switching context. Note that if other applications have allocated all 256 colors the client will fall back to using a private colormap.
Select Use Default to use the default window size, window colors or 256 color mapping setting specified with the Settings... command on the Option menu; refer to Window Settings....