The source images are different sizes. I'm drawing them to a CGRect that scales them down to a common width and a height that maintains the aspect ration of the image I'm drawing in. (For context, I'm basically creating a web sprite of very low-resolution copies of the input images all stacked on top of each other. I'm getting the result I want, just would like to resolve this error)

(Don't see a way to edit) Probably should have mentioned that this is a Mac app

OK, I've made the following changes, and (so far) it seems to be working... (Can you confirm this is what you were suggesting?) struct NavView: View { @Binding var main: Main @State private var selection: UUID? var body: some View { NavigationSplitView { ListView(main: $main, selection: $selection) } detail: { if let selection { DetailView(detail: $main.details.first(where: { $0.id == selection })!) } else { Text("Select a detail item to view") } } } } struct ListView: View { @Binding var main: Main @State private var addedDetailCount = 0 @Binding var selection: UUID? var body: some View { List($main.details, editActions: .move, selection: $selection) { $detail in NavigationLink(detail.title, value: detail) } .toolbar { Button( LocalizedStringKey("Add Detail"), systemImage: "plus" ) { addedDetailCount += 1 main.details.append( .init(title: "new Detail \(addedDetailCount)", description: "description")) } } } }