LESS(1)

       --mouse
              Enables mouse input: scrolling the mouse wheel down moves
              forward in the file, scrolling the mouse wheel up moves
              backwards in the file, and clicking the mouse sets the "#"
              mark to the line where the mouse is clicked.  The number
              of lines to scroll when the wheel is moved can be set by
              the --wheel-lines option.  Mouse input works only on
              terminals which support X11 mouse reporting, and on the
              Windows version of less.

  5. Using the mouse                                      *mouse-using*

  Don't forget to enable the mouse with this command: >
          :set mouse=a
  Otherwise Vim won't recognize the mouse in all modes (See 'mouse').

  Currently the mouse is supported for Unix in an xterm window, in a *BSD
  console with |sysmouse|, in a Linux console (with GPM |gpm-mouse|), for
  MS-DOS and in a Windows console.

                                                          *xterm-mouse-wheel*

  To use the mouse wheel in a new xterm you only have to make the scroll wheel
  work in your Xserver, as mentioned above.