I'm using star uml 2.6.0 in OSX 10.11.3 (El capitan).
At now, fork activity in activity diagram connects control flow as below image, which every start point of control flow positioned at middle of fork line.
In this example, it looks like there are no problem. But when folk line become long and multiplexed, it is hard to catch up the fork flow.
More intuitive and clear way is shown in the below image.
As fork line is bold, it clearly represents the base line of parallel flows. So the perpendicular control flow line would be much better.
I think that the best way is that making user to choice start point freely. Anyway, fixed start point of control flow seems need to be modify.