the #GtkCellAreaContext used to hold sizes for area.
the #GtkWidget that area is rendering on
the whole allocated area for area in widget for this row
the x position
the y position
where to store the inner allocated area of the returned cell renderer, or null.
the #GtkCellRenderer at x and y.
Gets the #GtkCellRenderer at x and y coordinates inside area and optionally returns the full cell allocation for it inside cell_area.