I posted this in the main thread but I think, I will repost it here, since this is the correct place:
Create a class in the class diagram, then make a child class, you get the usual parent child relationship, now mark the class with the mouse, hit del,
voila you have a tangeling connector.
The same works pretty much the same for the 1:n m:n relationship connectors.
There is also no way to delete the tangeling connector from the sidepane.
The same happens in the Use Case Diagram, to my knowlege.
As for the delete thing, I will try to reproduce it by tomorrow.