Sets the selection mark of a list view control.
int SetSelectionMark( int iIndex );
The zero-based index of the first item in a multiple selection.
The previous selection mark, or -1 if there was no selection mark.
This member function implements the behavior of the Win32 macro, ListView_SetSelectionMark, as described in the Windows SDK.
See the example for CListCtrl::GetSelectionMark.