Thanks for the tips, I will try it out. Since I can't reproduce it at will, I'm not sure when I'll secure the redisplay traces.
>> The place to start is in cedet/semantic/idle.el. The outward
>> call to the various work functions purposely does not use >> 'save-excursion' so tools like completion can move things around >> for you. > > Or maybe I don't understand what he meant.
I have seen the undesired scrolling with global-semantic-idle-completions-mode disabled. Specifically, with these Semantic submodes: