In this section:
%gd (Grid) is for program development only. It overlays a grid over the window and any items within it. This enables controls to be positioned using the %ap (Absolute Position) format. The grid is marked in small intervals corresponding to the average character size of the default font, with major divisions every 10 such units. The grid starts at the left and top margins, but extends over the right and bottom margins, since this may help in the placement of further controls.