BCGControlBar Pro for MFC
void CBCGPColorProp::EnableAutomaticButton ( LPCTSTR  lpszLabel,
COLORREF  colorAutomatic,
BOOL  bEnable = TRUE 
)

Enables the "automatic" button on the displayed color selection drop-down palette.

Parameters
lpszLabelSpecifies a button's text that will be displayed on the "automatic" button.
colorAutomaticSpecifies a new automatic color.
bEnableSpecifies whether the automatic button is enabled or not