In this section:
Both %hx (Horizontal Scroll Bar) and %vx (Vertical Scrollbar) have similar meaning and usage. %vx generates a vertical scroll bar on the right-hand side of the next control and %hx a horizontal scroll bar along the bottom of the next control. %hx and %vx should not be used with controls (like %eb (Edit Box) and %cw (ClearWin Window)) that have their own scroll bar mechanism. Three arguments must be supplied to both format codes. The first is an INTEGER argument that determines the 'page step'. This determines the amount the scroll box (also called the thumb) moves each time the left mouse button is pressed inside the scroll bar region. You would normally link this value to the effect of a 'page change' in the control. The second argument is the maximum value (call this max say) that the scroll bar may generate. The third argument holds the current value of the scroll bar. This is of type INTEGER and will be in the range 0 to (max - 1). A call-back function is provided when the caret modifier is used. See also %hx (Horizontal Scroll Bar) and %vx (Vertical Scrollbar) .