diff --git a/src/Uno.UI.RuntimeTests.Engine.Library/Engine/ExternalRunner/RuntimeTestEmbeddedRunner.cs b/src/Uno.UI.RuntimeTests.Engine.Library/Engine/ExternalRunner/RuntimeTestEmbeddedRunner.cs
index e963259..3172730 100644
--- a/src/Uno.UI.RuntimeTests.Engine.Library/Engine/ExternalRunner/RuntimeTestEmbeddedRunner.cs
+++ b/src/Uno.UI.RuntimeTests.Engine.Library/Engine/ExternalRunner/RuntimeTestEmbeddedRunner.cs
@@ -55,6 +55,19 @@ public static void AutoStartTests()
 		if (Environment.GetEnvironmentVariable("UNO_RUNTIME_TESTS_RUN_TESTS") is { } testsConfig
 			&& Environment.GetEnvironmentVariable("UNO_RUNTIME_TESTS_OUTPUT_PATH") is { } outputPath)
 		{
+			if (bool.TryParse(testsConfig, out var runTests))
+			{
+				if (runTests)
+				{
+					testsConfig = string.Empty; // Do not treat "true" as a filter.
+				}
+				else
+				{
+					Trace("Application has been configured to **NOT** start runtime-test, aborting runtime-test embedded runner.");
+					return;
+				}
+			}
+
 			Trace($"Application configured to start runtime-tests (Output={outputPath} | Config={testsConfig}).");
 
 			var outputKind = Enum.TryParse<TestResultKind>(Environment.GetEnvironmentVariable("UNO_RUNTIME_TESTS_OUTPUT_KIND"), ignoreCase: true, out var kind)
diff --git a/src/Uno.UI.RuntimeTests.Engine.Library/Engine/ExternalRunner/_Private/SecondaryApp.cs b/src/Uno.UI.RuntimeTests.Engine.Library/Engine/ExternalRunner/_Private/SecondaryApp.cs
index 4216c7b..2009fae 100644
--- a/src/Uno.UI.RuntimeTests.Engine.Library/Engine/ExternalRunner/_Private/SecondaryApp.cs
+++ b/src/Uno.UI.RuntimeTests.Engine.Library/Engine/ExternalRunner/_Private/SecondaryApp.cs
@@ -98,7 +98,7 @@ internal static partial class SecondaryApp
 		childStartInfo.EnvironmentVariables["UNO_RUNTIME_TESTS_RUN_TESTS"] = configJson;
 		childStartInfo.EnvironmentVariables["UNO_RUNTIME_TESTS_OUTPUT_PATH"] = testOutput;
 		childStartInfo.EnvironmentVariables["UNO_RUNTIME_TESTS_OUTPUT_KIND"] = "UnoRuntimeTests"; // "NUnit"
-		childStartInfo.EnvironmentVariables["UNO_RUNTIME_TESTS_IS_SECONDARY_APP"] = "true"; // "NUnit"
+		childStartInfo.EnvironmentVariables["UNO_RUNTIME_TESTS_IS_SECONDARY_APP"] = "true";
 
 		var childProcess = new global::System.Diagnostics.Process { StartInfo = childStartInfo };
 
diff --git a/src/Uno.UI.RuntimeTests.Engine.Library/Engine/UI/UnitTestsControl.cs b/src/Uno.UI.RuntimeTests.Engine.Library/Engine/UI/UnitTestsControl.cs
index 6adbd31..6c53545 100644
--- a/src/Uno.UI.RuntimeTests.Engine.Library/Engine/UI/UnitTestsControl.cs
+++ b/src/Uno.UI.RuntimeTests.Engine.Library/Engine/UI/UnitTestsControl.cs
@@ -527,6 +527,7 @@ private void EnableConfigPersistence()
 				{
 					consoleOutput.IsChecked = config.IsConsoleOutputEnabled;
 					runIgnored.IsChecked = config.IsRunningIgnored;
+					showSecondaryApp.IsChecked = config.IsSecondaryAppVisible;
 					retry.IsChecked = config.Attempts > 1;
 					testFilter.Text = config.Filter;
 				}
@@ -548,6 +549,8 @@ private void ListenConfigChanged()
 		runIgnored.Unchecked += (snd, e) => StoreConfig();
 		retry.Checked += (snd, e) => StoreConfig();
 		retry.Unchecked += (snd, e) => StoreConfig();
+		showSecondaryApp.Checked += (snd, e) => StoreConfig();
+		showSecondaryApp.Unchecked += (snd, e) => StoreConfig();
 		testFilter.TextChanged += (snd, e) => StoreConfig();
 
 		void StoreConfig()
@@ -561,6 +564,7 @@ private UnitTestEngineConfig BuildConfig()
 	{
 		var isConsoleOutput = consoleOutput.IsChecked ?? false;
 		var isRunningIgnored = runIgnored.IsChecked ?? false;
+		var isSecondaryAppVisible = showSecondaryApp.IsChecked;
 		var attempts = (retry.IsChecked ?? true) ? UnitTestEngineConfig.DefaultRepeatCount : 1;
 		var filter = testFilter.Text.Trim();
 		if (string.IsNullOrEmpty(filter))
@@ -573,6 +577,7 @@ private UnitTestEngineConfig BuildConfig()
 			Filter = filter,
 			IsConsoleOutputEnabled = isConsoleOutput,
 			IsRunningIgnored = isRunningIgnored,
+			IsSecondaryAppVisible = isSecondaryAppVisible,
 			Attempts = attempts,
 		};
 	}
@@ -749,7 +754,7 @@ private async Task ExecuteTestsForInstance(
 
 				config = config with { Filter = $"{testClassInfo.Type.FullName} & ({config.Filter})" };
 
-				var results = await SecondaryApp.RunTest(config, ct, isAppVisible: Debugger.IsAttached);
+				var results = await SecondaryApp.RunTest(config, ct, isAppVisible: config.IsSecondaryAppVisible ?? Debugger.IsAttached);
 				foreach (var result in results)
 				{
 					ReportTestResult(result);
diff --git a/src/Uno.UI.RuntimeTests.Engine.Library/Engine/UI/UnitTestsControl.xaml b/src/Uno.UI.RuntimeTests.Engine.Library/Engine/UI/UnitTestsControl.xaml
index 0ed0de4..013a4c7 100644
--- a/src/Uno.UI.RuntimeTests.Engine.Library/Engine/UI/UnitTestsControl.xaml
+++ b/src/Uno.UI.RuntimeTests.Engine.Library/Engine/UI/UnitTestsControl.xaml
@@ -71,6 +71,11 @@
 									IsChecked="True"
 									not_skia:Content="➰ Auto retry"
 									skia:Content="Auto retry" />
+								<ToggleButton
+									x:Name="showSecondaryApp"
+									IsThreeState="True"
+									not_skia:Content="🪟 Show 2nd app"
+									skia:Content="Show 2nd app" />
 							</StackPanel>
 						</Flyout>
 					</Button.Flyout>
diff --git a/src/Uno.UI.RuntimeTests.Engine.Library/Engine/UnitTestEngineConfig.cs b/src/Uno.UI.RuntimeTests.Engine.Library/Engine/UnitTestEngineConfig.cs
index 9f54485..af9f3b4 100644
--- a/src/Uno.UI.RuntimeTests.Engine.Library/Engine/UnitTestEngineConfig.cs
+++ b/src/Uno.UI.RuntimeTests.Engine.Library/Engine/UnitTestEngineConfig.cs
@@ -25,6 +25,8 @@ public record UnitTestEngineConfig
 	public bool IsConsoleOutputEnabled { get; init; }
 
 	public bool IsRunningIgnored { get; init; }
+
+	public bool? IsSecondaryAppVisible { get; init; }
 }
 
 #endif
\ No newline at end of file