set_icon_from_icon_name
Description:
Sets the icon shown in the entry at the specified position from the current icon theme.
If the icon name isn’t known, a “broken image” icon will be displayed instead.
If icon_name is null, no icon will be shown in the specified position.
Parameters:
| this | 
           A `GtkEntry`  | 
      
| icon_pos | 
           The position at which to set the icon  | 
      
| icon_name | 
           An icon name  |