Every time I click a face I store it in a container (like a TopTools_MapOfShape for example). Then when it's clicked again ,it allows me to know if such a face has been previously clicked or not. However I have the feeling that every time a face is clicked, it is not the original face that is returned but a copy of it. So I can never know if it has been clicked before or not... and it looks like the container stores several times the same face. Any hints ?