BCGControlBar Pro for MFC
UINT BCGM_ON_TOGGLE_RIBBON_MINIMIZE_STATE

Sent to Ribbon's parent when a Ribbon minimize state has been changed.

Parameters
wParamTRUE - if Ribbon is minimized, FALSE - if not.
lParamthis parameter is not used.
Returns
the return value is ignored.

The framework sends BCGM_ON_TOGGLE_RIBBON_MINIMIZE_STATE registered message to the Ribbon's parent when a Ribbon minimize state has been changed.