Offset: 64 (&40)
Set up by: ZapRedraw_GetRectangle, ZapRedraw_RedrawWindow
This is the vertical scroll offset in rectangle of characters given in r_data
of top left of redraw rectangle. This is in pixels from the top of the
characters. Note that in single height mode each line is r_charh+r_linesp
pixels high and in double height mode each line is 2*(r_charh+r_linesp)
pixels high.