Hey,
I've updated from NGUI 3.0.6f7 and I can tell you that a lot of stuff, especially how details work have changed.
Now I was wondering why a UILabel with Overflowmode set to ResizeHeight gets its width resized and I found that in UILabel.MakePixelPerfect "mWidth = 100000" and afterwards "mWidth = Mathf.Max(w, minX)", means that it can get wider. I don't have any idea why ambigiousFont != null.
Any help on this topic?