When visible, the grid is a set of points laid out in vertical and horizontal lines. The distance between grid points (vertical and horizontal grid units), whether visible or invisible, is defined by using the GRID-UNIT-HEIGHT-CHARS, GRID-UNIT-HEIGHT-PIXELS, GRID-UNIT-WIDTH-CHARS, and GRID-UNIT-WIDTH-PIXELS attributes. What grid points are visible is determined by the GRID-FACTOR-VERTICAL and GRID-FACTOR-HORIZONTAL attributes, which define the spacing between the visible vertical and horizontal lines of grid points.
When used with scrollable frames, some grid points might not be visible.
