get_position
Description:
Gets the position in the model that this currently displays.
If this is unbound, `GTK_INVALID_LIST_POSITION` is returned.
Parameters:
| this | a listitem | 
Returns:
| The position of this item | 
Gets the position in the model that this currently displays.
If this is unbound, `GTK_INVALID_LIST_POSITION` is returned.
| this | a listitem | 
| The position of this item |