MQL5 ReferenceStandard LibraryPanels and DialogsCScrollOnShow CreateOnEventMinPosMaxPosCurrPosCreateBackCreateIncCreateDecCreateThumbOnClickIncOnClickDecOnShowOnHideOnChangePosOnThumbDragStartOnThumbDragProcessOnThumbDragEndCalcPos OnShow The virtual handler of the control "Show" event. virtual bool OnShow() Return Value true - event processed, otherwise - false. OnClickDec OnHide