MQL5 ReferenceStandard LibraryPanels and DialogsCCheckGroupOnChangeItem CreateOnEventAddItemValueCreateButtonOnVScrollShowOnVScrollHideOnScrollLineDownOnScrollLineUpOnChangeItemRedrawRowState OnChangeItem The virtual handler of the control "ChangeItem" (item change) internal event. virtual bool OnChangeItem( const int index // index ) Parameters index [in] Index of the changed item. Return Value true - event processed, otherwise - false. OnScrollLineUp Redraw