Add performance stress testing example for future expansion

Examples/StressTest/StressTestApp.swift

@@ -0,0 +1,67 @@
+import GtkBackend
+import SwiftCrossUI
+
+class StressTestState: Observable {
+    @Observed
+    var tab = 0
+
+    @Observed
+    var values: [Int: [String]] = [:]
+
+    let options: [String] = [
+        "red",
+        "green",
+        "blue",
+        "tower",
+        "power",
+        "flower",
+        "one",
+        "two",
+        "three",
+        "foo",
+        "bar",
+        "baz",
+    ]
+}
+
+@main
+struct StressTestApp: App {
+    typealias Backend = GtkBackend
+
+    let identifier = "dev.stackotter.StressTestApp"
+
+    let state = StressTestState()
+
+    let windowProperties = WindowProperties(
+        title: "StressTestApp",
+        defaultSize: WindowProperties.Size(400, 400),
+        resizable: true
+    )
+
+    var body: some View {
+        NavigationSplitView {
+            VStack {
+                Button("List 1") { state.tab = 0 }
+                Button("List 2") { state.tab = 1 }
+            }.padding(10)
+        } detail: {
+            VStack {
+                Button("Generate") {
+                    var values: [String] = []
+                    for _ in 0..<1000 {
+                        values.append(state.options.randomElement()!)
+                    }
+
+                    state.values[state.tab] = values
+                }
+                if let values = state.values[state.tab] {
+                    ScrollView {
+                        ForEach(values) { value in
+                            Text(value)
+                        }
+                    }
+                }
+            }.padding(10)
+        }
+    }
+}

Package.swift

@@ -244,6 +244,11 @@ let package = Package(
             dependencies: exampleDependencies,
             path: "Examples/Spreadsheet"
         ),
+        .executableTarget(
+            name: "StressTestExample",
+            dependencies: exampleDependencies,
+            path: "Examples/StressTest"
+        ),
 
         .testTarget(
             name: "SwiftCrossUITests",