request_renderer
Description:
public void request_renderer (CellRenderer renderer, Orientation orientation, Widget widget, int for_size, out int minimum_size, out int natural_size)
  
  This is a convenience function for `GtkCellArea` implementations to request size for cell renderers.
It’s important to use this function to request size and then use inner_cell_area at render and event time since this function will add padding around the cell for focus painting.
Parameters:
| this | a `GtkCellArea` | 
| renderer | the `GtkCellRenderer` to request size for | 
| orientation | the `GtkOrientation` in which to request size | 
| widget | the `GtkWidget` that this is rendering onto | 
| for_size | the allocation contextual size to request for, or -1 if the base request for the orientation is to be returned. | 
| minimum_size | location to store the minimum size | 
| natural_size | location to store the natural size |