This variable applies only in text-mode environments. PAGED_LIST_SCROLL_BAR can be set to -1, 0, or 1. The default value is -1. When set to -1, the vertical scroll bar is displayed to the right of a paged list box if the user interface configuration supports a mouse. Otherwise, the right border appears just like the left border. The appearance depends on whether the NO-BOX style is set and the values of the FULL_BOXES and LISTS_UNBOXED configuration variable settings.
The runtime internally calls the W$MOUSE library routine with the TEST-MOUSE-PRESENCE op-code to determine whether the user interface supports a mouse. Note that mouse support is available for X terminals only if the a_termcap entry includes the km function. See Mouse Support for X Terminals for more information.
When PAGED_LIST_SCROLL_BAR is set to 1, the vertical scroll bar is always displayed to the right of a paged list box. When set to 0, the vertical scroll bar is never displayed to the right of a paged list box.