How do I get the SIP call flow diagrams to expand into more space?

When I bring up the SIP Call Flow diagram, it is too cramped to be usable. I can expand the pop-up window. The center bar that is the boundary between the "comment" on the right and the diagram on the left is live. However, the bar can be moved to the left, making the diagram smaller, but not to the right, making the diagram larger.

Is this a bug or am I missing something?

-Bob