The system hides and disables a standard scroll bar when equal minimum and maximum values are specified. The system also hides and disables a standard scroll bar if you specify a page size that includes the entire scroll range of the scroll bar. This is the way to temporarily hide a scroll bar when it is not needed for the content of the client area. There is no need to make scrolling requests through the scroll bar when it is hidden. The system enables the scroll bar and shows it again when you set the minimum and maximum values to unequal values or when the page size that does not include the entire scroll range. The ShowScrollBar function can also be used to hide or show a scroll bar. It does not affect the scroll bar's range, page size, or scroll box position.
The EnableScrollBar function can be used to disable one or both arrows of a scroll bar. An application displays disabled arrows in gray and does not respond to user input.