BCGControlBar Pro for MFC
UINT BCGM_ON_CLICK_WINUI_NAV_BACK_BUTTON

The message is sent to the owner of WinUI Tiles (CBCGPWinUITiles) when the user clicks a navigation "Back" button.

Parameters
wParamcontains the control ID of the WinUI Tiles.
lParamthis parameter is ignored.
Returns
The return value is ignored.

The framework doesn't send BCGM_ON_CLICK_WINUI_NAV_BACK_BUTTON message if WinUI tile has an active view. In this case the view is automatically closed upon clicking the navigation "Back" button and control returns to initial ("Start") page.