In response to that old thread:
No, we do not handle the way SketchUp on Mac handles multiple SU instances being open at the same time... it will cause scene corruption, crashes, and other horrible things to happen... You get 1 SketchUp instance only, Thomthom's utility probably won't do any good in this instance at all. Just don't do it. One SU window only on OSX if V-Ray is loaded.
In response to this thread:
I have no idea what that white dialog is, and I am unable to reproduce it so far on my own machine.