BCGControlBar Pro for MFC
BOOL CBCGPMiniFrameWnd::m_bUseSaveBits

Specifies whether to register the window class with CS_SAVEBITS or not.

m_bUseSaveBits is a static member. You can set it to TRUE and miniframe window class will be registered with CS_SAVEBITS style. This may help in reducing flickering when the user drags a toolbar.