BCGControlBar Pro for MFC
void CBCGPRibbonPaletteButton::SetPalette ( CBCGPToolBarImages imagesPalette,
CBCGPToolBarImages pImagesPaletteSimplified = NULL 

Attaches a palette (gallery) to the ribbon palette button.

Use this method to attach a gallery to the button on the fly.

imagesPaletteImages list with palette (gallery) icons.
pImagesPaletteSimplifiedA pointer to image list containing gallery images (displayed in the Ribbon simplified mode).