Describes the Ribbon bar gallery icons appearance.

Enumerator
BCGPRibbonGalleryIconsLook_Original	Don't change gallery icons.
BCGPRibbonGalleryIconsLook_Default	Same appearance as other Ribbon icons (specified by CBCGPRibbonBar::SetImagesLuminosity or CBCGPRibbonBar::SetImagesLuminosityInDarkThemes)
BCGPRibbonGalleryIconsLook_Invert	Gallery icons are inverted.
BCGPRibbonGalleryIconsLook_Simplified	Gallery icons are simplified.