[Interaction Use:012]: Special situation for message with gates to or from a graphically covered lifeline

When a message attached to a gate which other end is on a lifeline that is graphically covered by the interaction use, an orthogonal path around the shape of the interaction use, from sent event to receive event, will be used to connect both ends of the message.

If after changes in the list of covered lifelines graphically uncover a lifeline and there is no need for an orthogonal message path as described above, a straight message should be used instead, and fragments will be pushed up to achieve that.