Annoying popup window in Xcode Previews when the initial controller of the main storyboard is a macOS window

I started a project targeting macOS and used Storyboard app lifecycle. I also used Xcode Previews in this project.

If I:

  • Keep the entry point of the main storyboard to a window controller. (as default setup in macOS),
  • Turn the Xcode window into full-screen,

That window controller would pop up its window every time Xcode Previews refreshes.

I tested in Xcode 26.3 RC and many versions before.

Annoying popup window in Xcode Previews when the initial controller of the main storyboard is a macOS window
 
 
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