mouse   The  m option controls the mouse parameters; it may be abbrevi‐
               ated to ’m’.  The parameters for the mouse  are  ‘acceleration’
               and ‘threshold’.  The acceleration can be specified as an inte‐
               ger, or as a simple fraction.  The mouse, or  whatever  pointer
               the  machine  is  connected to, will go ‘acceleration’ times as
               fast when it travels more than ‘threshold’ pixels  in  a  short
               time.   This  way,  the mouse can be used for precise alignment
               when it is moved slowly, yet it can be set to travel across the
               screen  in  a  flick  of  the  wrist when desired.  One or both
               parameters for the m option can be omitted, but if only one  is
               given,  it  will  be  interpreted  as  the acceleration.  If no
               parameters or the flag ’default’ is used, the  system  defaults
               will be set.

               If  the ‘threshold’ parameter is provided and 0, the ‘accelera‐
               tion’ parameter will be used in the exponent of a more  natural
               and  continous  formula, giving precise control for slow motion
               but big reach for fast motion, and a progresive transition  for
               motions  in  between.  Recommended ‘acceleration’ value in this
               case is 3/2 to 2, but not limited to that range.