code: func (g *Grid) SetOffset(rows, columns int) *Grid {
  	g.rowOffset, g.columnOffset = rows, columns
  	return g
  }
docs: // SetOffset sets the number of rows and columns which are skipped before
  // drawing the first grid cell in the top-left corner. As the grid will never
  // completely move off the screen, these values may be adjusted the next time
  // the grid is drawn. The actual position of the grid may also be adjusted such
  // that contained primitives that have focus are visible.