MQL5 ReferenceStandard LibraryPanels and DialogsCBmpButtonOnChange CreateBorderBmpNamesBmpOffNameBmpOnNameBmpPassiveNameBmpActiveNamePressedLockingOnSetZOrderOnCreateOnShowOnHideOnMoveOnChangeOnActivateOnDeactivateOnMouseDownOnMouseUp OnChange The virtual handler of control "Change" internal event. virtual bool OnChange() Return Value true - event processed, otherwise - false. OnMove OnActivate