BCGControlBar Pro for MFC
virtual void CBCGPVisualManager::OnDrawRibbonDefaultPaneButton ( CDC *  pDC,
CBCGPRibbonButton pButton 

Called by the framework to draw ribbon pane default button. Default button is displayed when a ribbon pane (panel) is stretched to its minimal size and there is no place to display panel's content. The panel's content is displayed on a drop down menu, which appears when user clicks the default button.

pDCA pointer to a device context.
pButtonA pointer to default button.