Re-entrant operation: Horizontal constraint creation.
Scenario: create contour, start horizontal constraint, select lines one after another. On the 3rd line, the operation is not restarted anymore.
Another scenario corrected:
Create a polyline
click on vertical constraint
click on first segment => V constraint added
click on another segment => V constraint added
click in the the background (not on a entitity)
=> Green OK disappear and sometimes the message : Modification of data structure outside of the transaction
