Windows 3.x color schemes are strings in CONTROL.INI, with BBGGRR hex values placed in a specific order depending on the version of Windows. The earliest known version of Windows to use this format is Windows 3.0 v1.33, while the final version of Windows to use this format would be 4.00.73g, a Milestone 5 build of Windows 95. Color schemes can be used on any version, regardless of the version of Windows it was made in.

This format is mostly unchanged in Windows NT.

Windows 3.1x Color Scheme Format:

Scheme=Background,AppWorkspace,Window,WindowText,MenuBar,MenuText,ActiveTitle,InactiveTitle,ActiveTitleText,ActiveBorder,InactiveBorder,WindowFrame,Scrollbars,ButtonFace,ButtonShadow,ButtonText,DisabledText,Highlight,HighlightText,InactiveTitleText,ButtonHilight

Example:
Windows Default (256)=A4A0A0,F0FBFF,FFFFFF,0,FFFFFF,0,F0C8A4,FFFFFF,0,C0C0C0,C0C0C0,0,C0C0C0,C0C0C0,808080,0,C0C0C0,F0C8A4,0,0,FFFFFF


Windows 3.0 Color Scheme Format:

Scheme=Background,AppWorkspace,Window,WindowText,MenuBar,MenuText,ActiveTitle,InactiveTitle,ActiveTitleText,ActiveBorder,InactiveBorder,WindowFrame,Scrollbars

Example: 
Windows Default (256)=A4A0A0,F0FBFF,FFFFFF,0,FFFFFF,0,F0C8A4,FFFFFF,0,C0C0C0,C0C0C0,0,C0C0C0


Windows Chicago Color Scheme Format:

Scheme=Background,AppWorkspace,Window,WindowText,MenuBar,MenuText,ActiveTitle,InactiveTitle,ActiveTitleText,ActiveBorder,InactiveBorder,WindowFrame,Scrollbars,ButtonFace,ButtonShadow,ButtonText,DisabledText,Highlight,HighlightText,InactiveTitleText,ButtonHilight,ButtonDkShadow,Dialog

Example:
Windows Default (256)=A4A0A0,F0FBFF,FFFFFF,0,FFFFFF,0,F0C8A4,FFFFFF,0,C0C0C0,C0C0C0,0,C0C0C0,C0C0C0,808080,0,C0C0C0,F0C8A4,0,0,FFFFFF,0,C0C0C0


Windows Default driver defined color scheme:

The default color scheme is defined in the OEMBIN resource section (usually the last resource type in a resource editor like eXeScope), which varies depending on driver. It defines the unchangable values for the buttons and highlight color in Windows 3.0, however ButtonHilight and InactiveTitleText are not supported in Windows 3.0.
The beginning of the color scheme section usually starts with 00 01 and the hex value of the scrollbar color.