UINT BCGM_ON_ERASE_COMPACT_SCROLLBAR

The framework sends BCGM_ON_ERASE_COMPACT_SCROLLBAR registered message to the scroll bar's owner when background of the hidden scroll bar need to be erased.

Parameters

wParam	control ID of scroll bar.
lParam	a pointer to CBCGPScrollBar class.

Returns

The return value is ignored.

You should process this message to implement owner draw toolbars.