BCGControlBar Pro for MFC
void CBCGPGridCtrl::EnableInvertSelOnCtrl ( BOOL  bInvertSel = TRUE)

Defines grid's behavior on single click with CTRL key pressed.

If this mode is enabled, an item is deselected when user clicks the selected item with Ctrl key pressed. Otherwise, the grid control tries to add clicked item to current selection.

bInvertSelSpecifies whether section should be inverted (TRUE), or not (FALSE).