In the scheduler, a line can remain without being connected to tasks.

[pascal-ballet]

In some rare cases, a line can hangout of any task

[jeancharles-roger]

How can I reproduce it ?

When I remove a task, the connected lines also are removed.

[pascal-ballet]

It occured once when a task is selected (not the origin of the arrow). But I cannot reproduce it again...

[jeancharles-roger]

There is somewhere a problem. If it happens again, please fill the conditions here.