Some changes and adding much more unit tests.

UnitTests/ApplicationTests.cs

@@ -372,5 +372,609 @@ namespace Terminal.Gui.Core {
 			// Shutdown must be called to safely clean up Application if Init has been called
 			Application.Shutdown ();
 		}
+
+		[Fact]
+		public void Application_RequestStop_With_Params_On_A_Not_MdiContainer_Always_Use_The_Application_Current ()
+		{
+			Init ();
+
+			var top1 = new Toplevel ();
+			var top2 = new Toplevel ();
+			var top3 = new Window ();
+			var top4 = new Window ();
+			var d = new Dialog ();
+
+			// top1, top2, top3, d1 = 4
+			var iterations = 4;
+
+			top1.Ready += () => {
+				Assert.Null (Application.MdiChildes);
+				Application.Run (top2);
+			};
+			top2.Ready += () => {
+				Assert.Null (Application.MdiChildes);
+				Application.Run (top3);
+			};
+			top3.Ready += () => {
+				Assert.Null (Application.MdiChildes);
+				Application.Run (top4);
+			};
+			top4.Ready += () => {
+				Assert.Null (Application.MdiChildes);
+				Application.Run (d);
+			};
+
+			d.Ready += () => {
+				Assert.Null (Application.MdiChildes);
+				// This will close the d because on a not MdiContainer the Application.Current it always used.
+				Application.RequestStop (top1);
+				Assert.True (Application.Current == d);
+			};
+
+			d.Closed += (e) => Application.RequestStop (top1);
+
+			Application.Iteration += () => {
+				Assert.Null (Application.MdiChildes);
+				if (iterations == 4) {
+					Assert.True (Application.Current == d);
+				} else if (iterations == 3) {
+					Assert.True (Application.Current == top4);
+				} else if (iterations == 2) {
+					Assert.True (Application.Current == top3);
+				} else if (iterations == 1) {
+					Assert.True (Application.Current == top2);
+				} else {
+					Assert.True (Application.Current == top1);
+				}
+				Application.RequestStop (top1);
+				iterations--;
+			};
+
+			Application.Run (top1);
+
+			Assert.Null (Application.MdiChildes);
+
+			Application.Shutdown ();
+		}
+
+		class Mdi : Toplevel {
+			public Mdi ()
+			{
+				IsMdiContainer = true;
+			}
+		}
+
+		[Fact]
+		public void MdiContainer_With_Toplevel_RequestStop_Balanced ()
+		{
+			Init ();
+
+			var mdi = new Mdi ();
+			var c1 = new Toplevel ();
+			var c2 = new Window ();
+			var c3 = new Window ();
+			var d = new Dialog ();
+
+			// MdiChild = c1, c2, c3
+			// d1 = 1
+			var iterations = 4;
+
+			mdi.Ready += () => {
+				Assert.Empty (Application.MdiChildes);
+				Application.Run (c1);
+			};
+			c1.Ready += () => {
+				Assert.Single (Application.MdiChildes);
+				Application.Run (c2);
+			};
+			c2.Ready += () => {
+				Assert.Equal (2, Application.MdiChildes.Count);
+				Application.Run (c3);
+			};
+			c3.Ready += () => {
+				Assert.Equal (3, Application.MdiChildes.Count);
+				Application.Run (d);
+			};
+
+			// More easy because the Mdi Container handles all at once
+			d.Ready += () => {
+				Assert.Equal (3, Application.MdiChildes.Count);
+				// This will not close the MdiContainer because d is a modal toplevel and will be closed.
+				mdi.RequestStop ();
+			};
+
+			// Now this will close the MdiContainer propagating through the MdiChildes.
+			d.Closed += (e) => {
+				mdi.RequestStop ();
+			};
+
+			Application.Iteration += () => {
+				if (iterations == 4) {
+					// The Dialog was not closed before and will be closed now.
+					Assert.True (Application.Current == d);
+					Assert.False (d.Running);
+				} else {
+					Assert.Equal (iterations, Application.MdiChildes.Count);
+					for (int i = 0; i < iterations; i++) {
+						Assert.Equal ((iterations - i + 1).ToString (), Application.MdiChildes [i].Id);
+					}
+				}
+				iterations--;
+			};
+
+			Application.Run (mdi);
+
+			Assert.Empty (Application.MdiChildes);
+
+			Application.Shutdown ();
+		}
+
+		[Fact]
+		public void MdiContainer_With_Application_RequestStop_MdiTop_With_Params ()
+		{
+			Init ();
+
+			var mdi = new Mdi ();
+			var c1 = new Toplevel ();
+			var c2 = new Window ();
+			var c3 = new Window ();
+			var d = new Dialog ();
+
+			// MdiChild = c1, c2, c3
+			// d1 = 1
+			var iterations = 4;
+
+			mdi.Ready += () => {
+				Assert.Empty (Application.MdiChildes);
+				Application.Run (c1);
+			};
+			c1.Ready += () => {
+				Assert.Single (Application.MdiChildes);
+				Application.Run (c2);
+			};
+			c2.Ready += () => {
+				Assert.Equal (2, Application.MdiChildes.Count);
+				Application.Run (c3);
+			};
+			c3.Ready += () => {
+				Assert.Equal (3, Application.MdiChildes.Count);
+				Application.Run (d);
+			};
+
+			// Also easy because the Mdi Container handles all at once
+			d.Ready += () => {
+				Assert.Equal (3, Application.MdiChildes.Count);
+				// This will not close the MdiContainer because d is a modal toplevel
+				Application.RequestStop (mdi);
+			};
+
+			// Now this will close the MdiContainer propagating through the MdiChildes.
+			d.Closed += (e) => Application.RequestStop (mdi);
+
+			Application.Iteration += () => {
+				if (iterations == 4) {
+					// The Dialog was not closed before and will be closed now.
+					Assert.True (Application.Current == d);
+					Assert.False (d.Running);
+				} else {
+					Assert.Equal (iterations, Application.MdiChildes.Count);
+					for (int i = 0; i < iterations; i++) {
+						Assert.Equal ((iterations - i + 1).ToString (), Application.MdiChildes [i].Id);
+					}
+				}
+				iterations--;
+			};
+
+			Application.Run (mdi);
+
+			Assert.Empty (Application.MdiChildes);
+
+			Application.Shutdown ();
+		}
+
+		[Fact]
+		public void MdiContainer_With_Application_RequestStop_MdiTop_Without_Params ()
+		{
+			Init ();
+
+			var mdi = new Mdi ();
+			var c1 = new Toplevel ();
+			var c2 = new Window ();
+			var c3 = new Window ();
+			var d = new Dialog ();
+
+			// MdiChild = c1, c2, c3 = 3
+			// d1 = 1
+			var iterations = 4;
+
+			mdi.Ready += () => {
+				Assert.Empty (Application.MdiChildes);
+				Application.Run (c1);
+			};
+			c1.Ready += () => {
+				Assert.Single (Application.MdiChildes);
+				Application.Run (c2);
+			};
+			c2.Ready += () => {
+				Assert.Equal (2, Application.MdiChildes.Count);
+				Application.Run (c3);
+			};
+			c3.Ready += () => {
+				Assert.Equal (3, Application.MdiChildes.Count);
+				Application.Run (d);
+			};
+
+			//More harder because it's sequential.
+			d.Ready += () => {
+				Assert.Equal (3, Application.MdiChildes.Count);
+				// Close the Dialog
+				Application.RequestStop ();
+			};
+
+			// Now this will close the MdiContainer propagating through the MdiChildes.
+			d.Closed += (e) => Application.RequestStop (mdi);
+
+			Application.Iteration += () => {
+				if (iterations == 4) {
+					// The Dialog still is the current top and we can't request stop to MdiContainer
+					// because we are not using parameter calls.
+					Assert.True (Application.Current == d);
+					Assert.False (d.Running);
+				} else {
+					Assert.Equal (iterations, Application.MdiChildes.Count);
+					for (int i = 0; i < iterations; i++) {
+						Assert.Equal ((iterations - i + 1).ToString (), Application.MdiChildes [i].Id);
+					}
+				}
+				iterations--;
+			};
+
+			Application.Run (mdi);
+
+			Assert.Empty (Application.MdiChildes);
+
+			Application.Shutdown ();
+		}
+
+		[Fact]
+		public void IsMdiChild_Testing ()
+		{
+			Init ();
+
+			var mdi = new Mdi ();
+			var c1 = new Toplevel ();
+			var c2 = new Window ();
+			var c3 = new Window ();
+			var d = new Dialog ();
+
+			Application.Iteration += () => {
+				Assert.False (mdi.IsMdiChild);
+				Assert.True (c1.IsMdiChild);
+				Assert.True (c2.IsMdiChild);
+				Assert.True (c3.IsMdiChild);
+				Assert.False (d.IsMdiChild);
+
+				mdi.RequestStop ();
+			};
+
+			Application.Run (mdi);
+
+			Application.Shutdown ();
+		}
+
+		[Fact]
+		public void Modal_Toplevel_Can_Open_Another_Modal_Toplevel_But_RequestStop_To_The_Caller_Also_Sets_Current_Running_To_False_Too ()
+		{
+			Init ();
+
+			var mdi = new Mdi ();
+			var c1 = new Toplevel ();
+			var c2 = new Window ();
+			var c3 = new Window ();
+			var d1 = new Dialog ();
+			var d2 = new Dialog ();
+
+			// MdiChild = c1, c2, c3 = 3
+			// d1, d2 = 2
+			var iterations = 5;
+
+			mdi.Ready += () => {
+				Assert.Empty (Application.MdiChildes);
+				Application.Run (c1);
+			};
+			c1.Ready += () => {
+				Assert.Single (Application.MdiChildes);
+				Application.Run (c2);
+			};
+			c2.Ready += () => {
+				Assert.Equal (2, Application.MdiChildes.Count);
+				Application.Run (c3);
+			};
+			c3.Ready += () => {
+				Assert.Equal (3, Application.MdiChildes.Count);
+				Application.Run (d1);
+			};
+			d1.Ready += () => {
+				Assert.Equal (3, Application.MdiChildes.Count);
+				Application.Run (d2);
+			};
+
+			d2.Ready += () => {
+				Assert.Equal (3, Application.MdiChildes.Count);
+				Assert.True (Application.Current == d2);
+				Assert.True (Application.Current.Running);
+				// Trying to close the Dialog1
+				d1.RequestStop ();
+			};
+
+			// Now this will close the MdiContainer propagating through the MdiChildes.
+			d1.Closed += (e) => {
+				Assert.True (Application.Current == d1);
+				Assert.False (Application.Current.Running);
+				mdi.RequestStop ();
+			};
+
+			Application.Iteration += () => {
+				if (iterations == 5) {
+					// The Dialog2 still is the current top and we can't request stop to MdiContainer
+					// because Dialog2 and Dialog1 must be closed first.
+					// Dialog2 will be closed in this iteration.
+					Assert.True (Application.Current == d2);
+					Assert.False (Application.Current.Running);
+					Assert.False (d1.Running);
+				} else if (iterations == 4) {
+					// Dialog1 will be closed in this iteration.
+					Assert.True (Application.Current == d1);
+					Assert.False (Application.Current.Running);
+				} else {
+					Assert.Equal (iterations, Application.MdiChildes.Count);
+					for (int i = 0; i < iterations; i++) {
+						Assert.Equal ((iterations - i + 1).ToString (), Application.MdiChildes [i].Id);
+					}
+				}
+				iterations--;
+			};
+
+			Application.Run (mdi);
+
+			Assert.Empty (Application.MdiChildes);
+
+			Application.Shutdown ();
+		}
+
+		[Fact]
+		public void Modal_Toplevel_Can_Open_Another_Not_Modal_Toplevel_But_RequestStop_To_The_Caller_Also_Sets_Current_Running_To_False_Too ()
+		{
+			Init ();
+
+			var mdi = new Mdi ();
+			var c1 = new Toplevel ();
+			var c2 = new Window ();
+			var c3 = new Window ();
+			var d1 = new Dialog ();
+			var c4 = new Toplevel ();
+
+			// MdiChild = c1, c2, c3, c4 = 4
+			// d1 = 1
+			var iterations = 5;
+
+			mdi.Ready += () => {
+				Assert.Empty (Application.MdiChildes);
+				Application.Run (c1);
+			};
+			c1.Ready += () => {
+				Assert.Single (Application.MdiChildes);
+				Application.Run (c2);
+			};
+			c2.Ready += () => {
+				Assert.Equal (2, Application.MdiChildes.Count);
+				Application.Run (c3);
+			};
+			c3.Ready += () => {
+				Assert.Equal (3, Application.MdiChildes.Count);
+				Application.Run (d1);
+			};
+			d1.Ready += () => {
+				Assert.Equal (3, Application.MdiChildes.Count);
+				Application.Run (c4);
+			};
+
+			c4.Ready += () => {
+				Assert.Equal (4, Application.MdiChildes.Count);
+				// Trying to close the Dialog1
+				d1.RequestStop ();
+			};
+
+			// Now this will close the MdiContainer propagating through the MdiChildes.
+			d1.Closed += (e) => {
+				mdi.RequestStop ();
+			};
+
+			Application.Iteration += () => {
+				if (iterations == 5) {
+					// The Dialog2 still is the current top and we can't request stop to MdiContainer
+					// because Dialog2 and Dialog1 must be closed first.
+					// Using request stop here will call the Dialog again without need
+					Assert.True (Application.Current == d1);
+					Assert.False (Application.Current.Running);
+					Assert.True (c4.Running);
+				} else {
+					Assert.Equal (iterations, Application.MdiChildes.Count);
+					for (int i = 0; i < iterations; i++) {
+						Assert.Equal ((iterations - i + (iterations == 4 && i == 0 ? 2 : 1)).ToString (),
+							Application.MdiChildes [i].Id);
+					}
+				}
+				iterations--;
+			};
+
+			Application.Run (mdi);
+
+			Assert.Empty (Application.MdiChildes);
+
+			Application.Shutdown ();
+		}
+
+		[Fact]
+		public void MoveCurrent_Returns_False_If_The_Current_And_Top_Parameter_Are_Both_With_Running_Set_To_False ()
+		{
+			Init ();
+
+			var mdi = new Mdi ();
+			var c1 = new Toplevel ();
+			var c2 = new Window ();
+			var c3 = new Window ();
+
+			// MdiChild = c1, c2, c3
+			var iterations = 3;
+
+			mdi.Ready += () => {
+				Assert.Empty (Application.MdiChildes);
+				Application.Run (c1);
+			};
+			c1.Ready += () => {
+				Assert.Single (Application.MdiChildes);
+				Application.Run (c2);
+			};
+			c2.Ready += () => {
+				Assert.Equal (2, Application.MdiChildes.Count);
+				Application.Run (c3);
+			};
+			c3.Ready += () => {
+				Assert.Equal (3, Application.MdiChildes.Count);
+				c3.RequestStop ();
+				c1.RequestStop ();
+			};
+			// Now this will close the MdiContainer propagating through the MdiChildes.
+			c1.Closed += (e) => {
+				mdi.RequestStop ();
+			};
+			Application.Iteration += () => {
+				if (iterations == 3) {
+					// The Current still is c3 because Current.Running is false.
+					Assert.True (Application.Current == c3);
+					Assert.False (Application.Current.Running);
+					// But the childes order were reorder by Running = false
+					Assert.True (Application.MdiChildes [0] == c3);
+					Assert.True (Application.MdiChildes [1] == c1);
+					Assert.True (Application.MdiChildes [^1] == c2);
+				} else if (iterations == 2) {
+					// The Current is c1 and Current.Running is false.
+					Assert.True (Application.Current == c1);
+					Assert.False (Application.Current.Running);
+					Assert.True (Application.MdiChildes [0] == c1);
+					Assert.True (Application.MdiChildes [^1] == c2);
+				} else if (iterations == 1) {
+					// The Current is c2 and Current.Running is false.
+					Assert.True (Application.Current == c2);
+					Assert.False (Application.Current.Running);
+					Assert.True (Application.MdiChildes [^1] == c2);
+				} else {
+					// The Current is mdi.
+					Assert.True (Application.Current == mdi);
+					Assert.Empty (Application.MdiChildes);
+				}
+				iterations--;
+			};
+
+			Application.Run (mdi);
+
+			Assert.Empty (Application.MdiChildes);
+
+			Application.Shutdown ();
+		}
+
+		[Fact]
+		public void MdiContainer_Throws_If_More_Than_One ()
+		{
+			Init ();
+
+			var mdi = new Mdi ();
+			var mdi2 = new Mdi ();
+
+			mdi.Ready += () => {
+				Assert.Throws<InvalidOperationException> (() => Application.Run (mdi2));
+				mdi.RequestStop ();
+			};
+
+			Application.Run (mdi);
+
+			Application.Shutdown ();
+		}
+
+		[Fact]
+		public void MdiContainer_Open_And_Close_Modal_And_Open_Not_Modal_Toplevels_Randomly ()
+		{
+			Init ();
+
+			var mdi = new Mdi ();
+			var logger = new Toplevel ();
+
+			var iterations = 1; // The logger
+			var running = true;
+			var stageCompleted = true;
+			var allStageClosed = false;
+			var mdiRequestStop = false;
+
+			mdi.Ready += () => {
+				Assert.Empty (Application.MdiChildes);
+				Application.Run (logger);
+			};
+
+			logger.Ready += () => Assert.Single (Application.MdiChildes);
+
+			Application.Iteration += () => {
+				if (stageCompleted && running) {
+					stageCompleted = false;
+					var stage = new Window () { Modal = true };
+
+					stage.Ready += () => {
+						Assert.Equal (iterations, Application.MdiChildes.Count);
+						stage.RequestStop ();
+					};
+
+					stage.Closed += (_) => {
+						if (iterations == 11) {
+							allStageClosed = true;
+						}
+						Assert.Equal (iterations, Application.MdiChildes.Count);
+						if (running) {
+							stageCompleted = true;
+
+							var rpt = new Window ();
+
+							rpt.Ready += () => {
+								iterations++;
+								Assert.Equal (iterations, Application.MdiChildes.Count);
+							};
+
+							Application.Run (rpt);
+						}
+					};
+
+					Application.Run (stage);
+
+				} else if (iterations == 11 && running) {
+					running = false;
+					Assert.Equal (iterations, Application.MdiChildes.Count);
+
+				} else if (!mdiRequestStop && running && !allStageClosed) {
+					Assert.Equal (iterations, Application.MdiChildes.Count);
+
+				} else if (!mdiRequestStop && !running && allStageClosed) {
+					Assert.Equal (iterations, Application.MdiChildes.Count);
+					mdiRequestStop = true;
+					mdi.RequestStop ();
+				} else {
+					Assert.Empty (Application.MdiChildes);
+				}
+			};
+
+			Application.Run (mdi);
+
+			Assert.Empty (Application.MdiChildes);
+
+			Application.Shutdown ();
+		}
 	}
 }

UnitTests/AssemblyInfo.cs

@@ -7,7 +7,7 @@ using Xunit;
 // Since Application is a singleton we can't run tests in parallel
 [assembly: CollectionBehavior (DisableTestParallelization = true)]
 
-// This class enables test functions annotaed with the [AutoInitShutdown] attribute to 
+// This class enables test functions annotated with the [AutoInitShutdown] attribute to 
 // automatically call Application.Init before called and Application.Shutdown after
 // 
 // This is necessary because a) Application is a singleton and Init/Shutdown must be called

UnitTests/PosTests.cs

@@ -296,37 +296,43 @@ namespace Terminal.Gui.Core {
 			var app = setup ();
 			app.button.Y = Pos.Left (app.win);
 			rs = Application.Begin (Application.Top);
-			Application.Run ();
+			// If Application.RunState is used then we must use Application.RunLoop with the rs parameter
+			Application.RunLoop (rs);
 			cleanup (rs);
 
 			app = setup ();
 			app.button.Y = Pos.X (app.win);
 			rs = Application.Begin (Application.Top);
-			Application.Run ();
+			// If Application.RunState is used then we must use Application.RunLoop with the rs parameter
+			Application.RunLoop (rs);
 			cleanup (rs);
 
 			app = setup ();
 			app.button.Y = Pos.Top (app.win);
 			rs = Application.Begin (Application.Top);
-			Application.Run ();
+			// If Application.RunState is used then we must use Application.RunLoop with the rs parameter
+			Application.RunLoop (rs);
 			cleanup (rs);
 
 			app = setup ();
 			app.button.Y = Pos.Y (app.win);
 			rs = Application.Begin (Application.Top);
-			Application.Run ();
+			// If Application.RunState is used then we must use Application.RunLoop with the rs parameter
+			Application.RunLoop (rs);
 			cleanup (rs);
 
 			app = setup ();
 			app.button.Y = Pos.Bottom (app.win);
 			rs = Application.Begin (Application.Top);
-			Application.Run ();
+			// If Application.RunState is used then we must use Application.RunLoop with the rs parameter
+			Application.RunLoop (rs);
 			cleanup (rs);
 
 			app = setup ();
 			app.button.Y = Pos.Right (app.win);
 			rs = Application.Begin (Application.Top);
-			Application.Run ();
+			// If Application.RunState is used then we must use Application.RunLoop with the rs parameter
+			Application.RunLoop (rs);
 			cleanup (rs);
 		}
 

UnitTests/ScenarioTests.cs

@@ -72,10 +72,12 @@ namespace Terminal.Gui {
 				var scenario = (Scenario)Activator.CreateInstance (scenarioClass);
 				scenario.Init (Application.Top, Colors.Base);
 				scenario.Setup ();
-				var rs = Application.Begin (Application.Top);
+				// There is no need to call Application.Begin because Init already creates the Application.Top
+				// If Application.RunState is used then the Application.RunLoop must also be used instead Application.Run.
+				//var rs = Application.Begin (Application.Top);
 				scenario.Run ();
 
-				Application.End (rs);
+				//Application.End (rs);
 
 				// Shutdown must be called to safely clean up Application if Init has been called
 				Application.Shutdown ();
@@ -100,7 +102,7 @@ namespace Terminal.Gui {
 			Assert.NotEmpty (scenarioClasses);
 
 			var item = scenarioClasses.FindIndex (t => Scenario.ScenarioMetadata.GetName (t).Equals ("Generic", StringComparison.OrdinalIgnoreCase));
-			var scenarioClass = scenarioClasses[item];
+			var scenarioClass = scenarioClasses [item];
 			// Setup some fake keypresses 
 			// Passing empty string will cause just a ctrl-q to be fired
 			int stackSize = CreateInput ("");
@@ -132,10 +134,12 @@ namespace Terminal.Gui {
 			var scenario = (Scenario)Activator.CreateInstance (scenarioClass);
 			scenario.Init (Application.Top, Colors.Base);
 			scenario.Setup ();
-			var rs = Application.Begin (Application.Top);
+			// There is no need to call Application.Begin because Init already creates the Application.Top
+			// If Application.RunState is used then the Application.RunLoop must also be used instead Application.Run.
+			//var rs = Application.Begin (Application.Top);
 			scenario.Run ();
 
-			Application.End (rs);
+			//Application.End (rs);
 
 			Assert.Equal (0, abortCount);
 			// # of key up events should match # of iterations

UnitTests/StackExtensionsTests.cs

@@ -0,0 +1,192 @@
+using System;
+using System.Collections.Generic;
+using Xunit;
+
+namespace Terminal.Gui.Core {
+	public class StackExtensionsTests {
+		[Fact]
+		public void Stack_Toplevels_CreateToplevels ()
+		{
+			Stack<Toplevel> toplevels = CreateToplevels ();
+
+			int index = toplevels.Count - 1;
+			foreach (var top in toplevels) {
+				if (top.GetType () == typeof (Toplevel)) {
+					Assert.Equal ("Top", top.Id);
+				} else {
+					Assert.Equal ($"w{index}", top.Id);
+				}
+				index--;
+			}
+
+			var tops = toplevels.ToArray ();
+
+			Assert.Equal ("w4", tops [0].Id);
+			Assert.Equal ("w3", tops [1].Id);
+			Assert.Equal ("w2", tops [2].Id);
+			Assert.Equal ("w1", tops [3].Id);
+			Assert.Equal ("Top", tops [^1].Id);
+		}
+
+		[Fact]
+		public void Stack_Toplevels_Replace ()
+		{
+			Stack<Toplevel> toplevels = CreateToplevels ();
+
+			var valueToReplace = new Window () { Id = "w1" };
+			var valueToReplaceWith = new Window () { Id = "new" };
+			ToplevelEqualityComparer comparer = new ToplevelEqualityComparer ();
+
+			toplevels.Replace (valueToReplace, valueToReplaceWith, comparer);
+
+			var tops = toplevels.ToArray ();
+
+			Assert.Equal ("w4", tops [0].Id);
+			Assert.Equal ("w3", tops [1].Id);
+			Assert.Equal ("w2", tops [2].Id);
+			Assert.Equal ("new", tops [3].Id);
+			Assert.Equal ("Top", tops [^1].Id);
+		}
+
+		[Fact]
+		public void Stack_Toplevels_Swap ()
+		{
+			Stack<Toplevel> toplevels = CreateToplevels ();
+
+			var valueToSwapFrom = new Window () { Id = "w3" };
+			var valueToSwapTo = new Window () { Id = "w1" };
+			ToplevelEqualityComparer comparer = new ToplevelEqualityComparer ();
+			toplevels.Swap (valueToSwapFrom, valueToSwapTo, comparer);
+
+			var tops = toplevels.ToArray ();
+
+			Assert.Equal ("w4", tops [0].Id);
+			Assert.Equal ("w1", tops [1].Id);
+			Assert.Equal ("w2", tops [2].Id);
+			Assert.Equal ("w3", tops [3].Id);
+			Assert.Equal ("Top", tops [^1].Id);
+		}
+
+		[Fact]
+		public void Stack_Toplevels_MoveNext ()
+		{
+			Stack<Toplevel> toplevels = CreateToplevels ();
+
+			toplevels.MoveNext ();
+
+			var tops = toplevels.ToArray ();
+
+			Assert.Equal ("w3", tops [0].Id);
+			Assert.Equal ("w2", tops [1].Id);
+			Assert.Equal ("w1", tops [2].Id);
+			Assert.Equal ("Top", tops [3].Id);
+			Assert.Equal ("w4", tops [^1].Id);
+		}
+
+		[Fact]
+		public void Stack_Toplevels_MovePrevious ()
+		{
+			Stack<Toplevel> toplevels = CreateToplevels ();
+
+			toplevels.MovePrevious ();
+
+			var tops = toplevels.ToArray ();
+
+			Assert.Equal ("Top", tops [0].Id);
+			Assert.Equal ("w4", tops [1].Id);
+			Assert.Equal ("w3", tops [2].Id);
+			Assert.Equal ("w2", tops [3].Id);
+			Assert.Equal ("w1", tops [^1].Id);
+		}
+
+		[Fact]
+		public void ToplevelEqualityComparer_GetHashCode ()
+		{
+			Stack<Toplevel> toplevels = CreateToplevels ();
+
+			// Only allows unique keys
+			HashSet<int> hCodes = new HashSet<int> ();
+
+			foreach (var top in toplevels) {
+				Assert.True (hCodes.Add (top.GetHashCode ()));
+			}
+		}
+
+		[Fact]
+		public void Stack_Toplevels_FindDuplicates ()
+		{
+			Stack<Toplevel> toplevels = CreateToplevels ();
+			ToplevelEqualityComparer comparer = new ToplevelEqualityComparer ();
+
+			toplevels.Push (new Toplevel () { Id = "w4" });
+			toplevels.Push (new Toplevel () { Id = "w1" });
+
+			var dup = toplevels.FindDuplicates (comparer).ToArray ();
+
+			Assert.Equal ("w4", dup [0].Id);
+			Assert.Equal ("w1", dup [^1].Id);
+		}
+
+		[Fact]
+		public void Stack_Toplevels_Contains ()
+		{
+			Stack<Toplevel> toplevels = CreateToplevels ();
+			ToplevelEqualityComparer comparer = new ToplevelEqualityComparer ();
+
+			Assert.True (toplevels.Contains (new Window () { Id = "w2" }, comparer));
+			Assert.False (toplevels.Contains (new Toplevel () { Id = "top2" }, comparer));
+		}
+
+		[Fact]
+		public void Stack_Toplevels_MoveTo ()
+		{
+			Stack<Toplevel> toplevels = CreateToplevels ();
+
+			var valueToMove = new Window () { Id = "w1" };
+			ToplevelEqualityComparer comparer = new ToplevelEqualityComparer ();
+
+			toplevels.MoveTo (valueToMove, 1, comparer);
+
+			var tops = toplevels.ToArray ();
+
+			Assert.Equal ("w4", tops [0].Id);
+			Assert.Equal ("w1", tops [1].Id);
+			Assert.Equal ("w3", tops [2].Id);
+			Assert.Equal ("w2", tops [3].Id);
+			Assert.Equal ("Top", tops [^1].Id);
+		}
+
+		[Fact]
+		public void Stack_Toplevels_MoveTo_From_Last_To_Top ()
+		{
+			Stack<Toplevel> toplevels = CreateToplevels ();
+
+			var valueToMove = new Window () { Id = "Top" };
+			ToplevelEqualityComparer comparer = new ToplevelEqualityComparer ();
+
+			toplevels.MoveTo (valueToMove, 0, comparer);
+
+			var tops = toplevels.ToArray ();
+
+			Assert.Equal ("Top", tops [0].Id);
+			Assert.Equal ("w4", tops [1].Id);
+			Assert.Equal ("w3", tops [2].Id);
+			Assert.Equal ("w2", tops [3].Id);
+			Assert.Equal ("w1", tops [^1].Id);
+		}
+
+
+		private Stack<Toplevel> CreateToplevels ()
+		{
+			Stack<Toplevel> toplevels = new Stack<Toplevel> ();
+
+			toplevels.Push (new Toplevel () { Id = "Top" });
+			toplevels.Push (new Window () { Id = "w1" });
+			toplevels.Push (new Window () { Id = "w2" });
+			toplevels.Push (new Window () { Id = "w3" });
+			toplevels.Push (new Window () { Id = "w4" });
+
+			return toplevels;
+		}
+	}
+}

UnitTests/ViewTests.cs

@@ -1332,5 +1332,43 @@ namespace Terminal.Gui.Views {
 			Assert.True (label.AutoSize);
 			Assert.Equal ("{X=0,Y=0,Width=28,Height=2}", label.Bounds.ToString ());
 		}
+
+		[Theory]
+		[InlineData (1)]
+		[InlineData (2)]
+		[InlineData (3)]
+		public void LabelChangeText_RendersCorrectly_Constructors (int choice)
+		{
+			var driver = new FakeDriver ();
+			Application.Init (driver, new FakeMainLoop (() => FakeConsole.ReadKey (true)));
+
+			try {
+				// Create a label with a short text 
+				Label lbl;
+				var text = "test";
+
+				if (choice == 1) {
+					// An object initializer should call the default constructor.
+					lbl = new Label { Text = text };
+				} else if (choice == 2) {
+					// Calling the default constructor followed by the object initializer.
+					lbl = new Label () { Text = text };
+				} else {
+					// Calling the Text constructor.
+					lbl = new Label (text);
+				}
+				lbl.ColorScheme = new ColorScheme ();
+				lbl.Redraw (lbl.Bounds);
+
+				// should have the initial text
+				Assert.Equal ('t', driver.Contents [0, 0, 0]);
+				Assert.Equal ('e', driver.Contents [0, 1, 0]);
+				Assert.Equal ('s', driver.Contents [0, 2, 0]);
+				Assert.Equal ('t', driver.Contents [0, 3, 0]);
+				Assert.Equal (' ', driver.Contents [0, 4, 0]);
+			} finally {
+				Application.Shutdown ();
+			}
+		}
 	}
 }