BCGControlBar Pro for MFC
UINT BCGM_CHANGE_TAB_SELECTION

This message is sent to the parent of CBCGPTabWnd object when user changed tabs selection.

Parameters
wParamthis parameter is not used.
lParama pointer to tabbed window (the sender)
Returns
the return value is ignored.

You should process this message to receive notifications from CBCGPTabWnd objects when tabs multiple selection was changed.