render_icon
Description:
Renders an icon of given size.
 The base of the icon is set by the last call to one of: 
        set_pixbuf, set_gicon, 
      set_icon_name or 
      set_stock_id. size cannot be lower than
      1.
Parameters:
| this | |
| widget | widget of which style settings may be used. | 
| size | size of the rendered icon. | 
Returns:
| A rendered pixbuf. The pixbuf belongs to this and should not be unreffed. |