When a space is scrolled, part of the text is not read. He goes to the edge.

solution: decrease direction to 0.95-0.97

shortcuts.c

559c559
<   double direction = 1;
---
>   double direction = 0.97;
562c562
<     direction = -1.0;
---
>     direction *= -1;

  /* compute the direction of scrolling */
  double direction = 0.97;
  if ((argument->n == LEFT) || (argument->n == FULL_LEFT) || (argument->n == HALF_LEFT) ||
      (argument->n == UP) || (argument->n == FULL_UP) || (argument->n == HALF_UP)) {
    direction *= -1;
  }

And it is better to make this variable convenient to change