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
/usr/local/plan9/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