simpleUML sequence diagrams non-intuitive method call arrows

I found the sequence diagram of simpleUML very useful - but:

why is there always an "anObject" ? I would like to define which is the first class.

then, it seems to draw method call lines that are not intuitive. I had MyClass.getInstance().addListener(...)
Then I got a method call arrow from anObject to MyClass (getInstance), then from Myclass to MyClassIF (addListener) - where it should go from anObject to MyClassIF.


M.