Clicking on an Interaction Operand causes it transfer to a parent fragment (#85)

Hi,

In a sequence diagram, I had and Alt fragment, and put an Opt fragment inside it. I put an Interaction Operand inside the Opt fragment.

Unfortunately, when I left- or right-click the Interaction Operand, it automatically gets transferred to the Alt fragment.

I'd like the Operand to stay in its original fragment, please. :)