I think it would be a good idea to have some form of identification marker highlight the users "chosen" bright star during the polar alignment, so that it is more easily recognizable. It can be easy to forget which star you are suppose to be moving towards the target, especially if there are large movements of the mount when adjusting the Alt/Az bolts on the mount.
What does double-clicking the star do? I wouldn't expect the PA / display code to able to track star movement between images while the mount itself is being moved.
I've found it easiest to move the mount *while* the image is being taken. That combined with small moves will let you see trails making it easier to follow a specific star.