The following worked for me: struct MyApp: App { var body: some SwiftUI.Scene { WindowGroup { ContentView() } .defaultSize(CGSize(width: 1000, height: 250)) } }

I was able to get it to work by tweaking the code to the following (thank you 'lorem ipsum' over at Stack Overflow!) Here's the corrected code: struct GlimpseVision: App { var body: some SwiftUI.Scene { WindowGroup { ContentView() } .defaultSize(CGSize(width: 1000, height: 250)) } }