strange behaviour with "decapsulate"

[thibaudk]

At the first decapsulation, both the parent interval and the previously encapsulated one are superimposed witch can be confusing.
I then pressed "ctrl+z" to undo the decapsulation, and then decapsulated again.
This time, the previously encapsulated interval is shrieked to the point of a single state, apparently still linked to the common sink but the connection is invisible. Moving it further to the wright and dropping it, it appears like a lone state. Trying to move it some more and the left limit of the invisible sink has moved to the dropping point.

[jcelerier]

should be fixed now