MOUSESCROLLSIZE(3)                             MOUSESCROLLSIZE(3)

     NAME
          mousescrollsize - compute mouse scroll increment

     SYNOPSIS
          #include <draw.h>

          int  mousescrollsize(int maxlines)

     DESCRIPTION
          Mousescrollsize computes the number of lines of text that
          should be scrolled in response to a mouse scroll wheel
          click.  Maxlines is the number of lines visible in the text
          window.

          The default scroll increment is one line.  This default can
          be overridden by setting the $mousescrollsize environment
          variable to an integer, which specifies a constant number of
          lines, or to a real number followed by a percent character,
          indicating that the scroll increment should be a percentage
          of the total number of lines in the window.  For example,
          setting $mousescrollsize to 50% causes a half-window scroll
          increment.

          Mousescrollsize is used by 9term(1) and acme(1) to set their
          scrolling behavior.

     SOURCE
          /src/libdraw/scroll.c

     SEE ALSO
          9term(1), acme(1)

     BUGS
          Libdraw expects up and down scroll wheel events to be
          expressed as clicks of mouse buttons 4 and 5, but the
          XFree86 default is to ignore the scroll wheel.  To enable
          the scroll wheel, change your InputDevice section of
          XF86Config-4 to look like:

               Section "InputDevice"
                    Identifier     "Mouse0"
                    Driver    "mouse"
                    Option    "Device" "/dev/psaux"

                    # next four lines enable scroll wheel as buttons 4 and 5
                    Option    "Buttons" "5"
                    Option    "Emulate3Buttons" "off"
                    Option    "Protocol" "ImPS/2"
                    Option    "ZAxisMapping" "4 5"
               EndSection

     MOUSESCROLLSIZE(3)                             MOUSESCROLLSIZE(3)