In portal, when the dropped representation is larger than the box used to contain it, the container title and button exit is not visible

[lfasani]

• I have checked that this bug has not yet been reported by someone else
• I have checked that this bug appears on Chrome
• I have specified the version :

• latest

Steps to reproduce

• create a portal representation

• drop a gantt representation inside
  -> KO : the cross icon is not visible
  

• move the vertical scroll
  -> KO: the upper part with the name of the representation is not visible anymore. It is not possible to move the representation containing box
  

Expected behavior

We should always see the upper bar containing the name of the representation and the cross button to remove the representation WITHOUT having to use the scroll bar