Whenever you add a new controller to the storyboard it stays on the screen indefinitely (even if the application is minimised).
I just updated to the beta channel (for unrelated reasons) and the issue seems to be resolved.
I cannot reproduce the described issue. Can you provide more detailed steps to reproduce? And perhaps your versoin information? In Xamarin/Visual Studio (Mac), version information can be obtained by navigating to: Xamarin/Visual Studio -> About Xamarin/Visual Studio -> Show Details -> Copy Information button.
I recorded the bug here youtu.be/EmRuWMX-msg and also attached the version information.
Probably the most important info is that I am on the stable channel (and up to date) and running 10.13 High Sierra.
This only happens when you add a new controller to the storyboard, if you move existing ones it works just fine. So it probably just is the drag & drop visualizer that doesn't hide once dropped.
E: This isn't limited to just views, every control I add to the storyboard has the same bug.
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