Im using storyboard in my app and TabViewController with three tabs. When I  put NSVisualEffectView in my views it works fine, but when I move my window, my VisualEffectView starting disappear. 
Settings for my visual effects are: Behind window, Dark an Active. I use IB to put them in my views.
If I use only one view without TabViewController NSVisualEffectView works just fine, but that TabViewController cause troubles. Can anyone please help?