Returns the underlying #GtkCellArea which might be cell_layout if called on a #GtkCellArea or might be null if no #GtkCellArea is used by cell_layout.
the cell area used by cell_layout, or null in case no cell area is used.
Returns the underlying #GtkCellArea which might be cell_layout if called on a #GtkCellArea or might be null if no #GtkCellArea is used by cell_layout.