code: func (v *Grid) AttachNextTo(child, sibling IWidget, side PositionType, width, height int) {
  	C.gtk_grid_attach_next_to(v.native(), child.toWidget(),
  		sibling.toWidget(), C.GtkPositionType(side), C.gint(width),
  		C.gint(height))
  }
docs: // AttachNextTo() is a wrapper around gtk_grid_attach_next_to().