diff --git a/main/external/xwt b/main/external/xwt
index 0b54869e244..e159b80639e 160000
--- a/main/external/xwt
+++ b/main/external/xwt
@@ -1 +1 @@
-Subproject commit 0b54869e24438f1b36aee977e799f0b82481ed7b
+Subproject commit e159b80639ec01d2551cbcb1e039b96dd592d2c8
diff --git a/main/src/addins/MacPlatform/MacPlatform.cs b/main/src/addins/MacPlatform/MacPlatform.cs
index a7047b4c4ac..48978a219e6 100644
--- a/main/src/addins/MacPlatform/MacPlatform.cs
+++ b/main/src/addins/MacPlatform/MacPlatform.cs
@@ -289,6 +289,8 @@ static void RegisterUncaughtExceptionHandler ()
 			NSSetUncaughtExceptionHandler (uncaughtHandler);
 		}
 
+		internal static List<IDisposable> AllObservers { get; } = new List<IDisposable> ();
+
 		public override Xwt.Toolkit LoadNativeToolkit ()
 		{
 			var loaded = NativeToolkitHelper.LoadCocoa ();
@@ -307,6 +309,10 @@ public override Xwt.Toolkit LoadNativeToolkit ()
 			var appDelegate = NSApplication.SharedApplication.Delegate as Xwt.Mac.AppDelegate;
 			if (appDelegate != null) {
 				appDelegate.Terminating += async (object o, TerminationEventArgs e) => {
+					foreach (var observer in AllObservers)
+						observer.Dispose ();
+					AllObservers.Clear ();
+
 					if (MonoDevelop.Ide.IdeApp.IsRunning) {
 						// If GLib the mainloop is still running that means NSApplication.Terminate() was called
 						// before Gtk.Application.Quit(). Cancel Cocoa termination and exit the mainloop.
@@ -319,6 +325,9 @@ public override Xwt.Toolkit LoadNativeToolkit ()
 						e.Reply = NSApplicationTerminateReply.Now;
 					}
 				};
+
+				// TODO: only attach this if coverage profiler is on
+				appDelegate.Terminate += () => Environment.Exit (0);
 				appDelegate.ShowDockMenu += AppDelegate_ShowDockMenu;
 			}
 
@@ -326,7 +335,7 @@ public override Xwt.Toolkit LoadNativeToolkit ()
 			SwizzleNSApplication ();
 
 			var nc = NSNotificationCenter.DefaultCenter;
-			notificationObservers.Add (nc.AddObserver ((NSString)"AtkCocoaAccessibilityEnabled", (NSNotification) => {
+			AllObservers.Add (nc.AddObserver ((NSString)"AtkCocoaAccessibilityEnabled", (NSNotification) => {
 				LoggingService.LogInfo ($"VoiceOver on {IdeTheme.AccessibilityEnabled}");
 				if (!IdeTheme.AccessibilityEnabled) {
 					ShowVoiceOverNotice ();
@@ -582,7 +591,7 @@ void InitApp (CommandManager commandManager)
 
 			if (MacSystemInformation.OsVersion >= MacSystemInformation.Mojave) {
 				IdeTheme.HighContrastThemeEnabled = GetIsHighContrastActive ();
-				notificationObservers.Add (NSApplication.SharedApplication.AddObserver ("effectiveAppearance", NSKeyValueObservingOptions.New, notif =>
+				AllObservers.Add (NSApplication.SharedApplication.AddObserver ("effectiveAppearance", NSKeyValueObservingOptions.New, notif =>
 					Core.Runtime.RunInMainThread (() => {
 						IdeTheme.HighContrastThemeEnabled = GetIsHighContrastActive ();
 						PatchGtkTheme ();
@@ -590,7 +599,7 @@ void InitApp (CommandManager commandManager)
 				));
 			} else {
 				IdeTheme.HighContrastThemeEnabled = false;
-				notificationObservers.Add (NSNotificationCenter.DefaultCenter.AddObserver (NSCell.ControlTintChangedNotification, notif => Core.Runtime.RunInMainThread (
+				AllObservers.Add (NSNotificationCenter.DefaultCenter.AddObserver (NSCell.ControlTintChangedNotification, notif => Core.Runtime.RunInMainThread (
 					delegate {
 						Styles.LoadStyle ();
 						PatchGtkTheme ();
diff --git a/main/src/addins/MacPlatform/MainToolbar/AwesomeBar.cs b/main/src/addins/MacPlatform/MainToolbar/AwesomeBar.cs
index 86af18a505f..c250fa03d3f 100644
--- a/main/src/addins/MacPlatform/MainToolbar/AwesomeBar.cs
+++ b/main/src/addins/MacPlatform/MainToolbar/AwesomeBar.cs
@@ -144,7 +144,7 @@ public override void ViewDidMoveToWindow ()
 		public override void ViewWillMoveToSuperview (NSView newSuperview)
 		{
 			if (Superview != null && superviewFrameChangeObserver != null) {
-				NSNotificationCenter.DefaultCenter.RemoveObserver (superviewFrameChangeObserver);
+				superviewFrameChangeObserver.Dispose ();
 				superviewFrameChangeObserver = null;
 
 				Superview.PostsFrameChangedNotifications = false;
diff --git a/main/src/addins/MacPlatform/MainToolbar/MainToolbar.cs b/main/src/addins/MacPlatform/MainToolbar/MainToolbar.cs
index 1626f472506..31727d974dc 100644
--- a/main/src/addins/MacPlatform/MainToolbar/MainToolbar.cs
+++ b/main/src/addins/MacPlatform/MainToolbar/MainToolbar.cs
@@ -192,12 +192,12 @@ public MainToolbar (Gtk.Window window)
 						item.MinSize = size;
 					}
 				});
-				NSNotificationCenter.DefaultCenter.AddObserver (NSWindow.DidResizeNotification, resizeAction, nswin);
-				NSNotificationCenter.DefaultCenter.AddObserver (NSWindow.DidEndLiveResizeNotification, resizeAction, nswin);
+				MacPlatformService.AllObservers.Add (NSNotificationCenter.DefaultCenter.AddObserver (NSWindow.DidResizeNotification, resizeAction, nswin));
+				MacPlatformService.AllObservers.Add (NSNotificationCenter.DefaultCenter.AddObserver (NSWindow.DidEndLiveResizeNotification, resizeAction, nswin));
 			}
 
-			NSNotificationCenter.DefaultCenter.AddObserver (NSWindow.WillEnterFullScreenNotification, (note) => IsFullscreen = true, nswin);
-			NSNotificationCenter.DefaultCenter.AddObserver (NSWindow.WillExitFullScreenNotification, (note) => IsFullscreen = false, nswin);
+			MacPlatformService.AllObservers.Add (NSNotificationCenter.DefaultCenter.AddObserver (NSWindow.WillEnterFullScreenNotification, (note) => IsFullscreen = true, nswin));
+			MacPlatformService.AllObservers.Add (NSNotificationCenter.DefaultCenter.AddObserver (NSWindow.WillExitFullScreenNotification, (note) => IsFullscreen = false, nswin));
 		}
 
 		internal void Initialize ()
diff --git a/main/src/addins/MacPlatform/MainToolbar/SearchBar.cs b/main/src/addins/MacPlatform/MainToolbar/SearchBar.cs
index 3acaf0a4866..5f010142e0c 100644
--- a/main/src/addins/MacPlatform/MainToolbar/SearchBar.cs
+++ b/main/src/addins/MacPlatform/MainToolbar/SearchBar.cs
@@ -243,7 +243,7 @@ void UpdateLayout ()
 
 		void Initialize ()
 		{
-			NSNotificationCenter.DefaultCenter.AddObserver (NSWindow.DidResignKeyNotification, notification => Runtime.RunInMainThread (() => {
+			MacPlatformService.AllObservers.Add (NSNotificationCenter.DefaultCenter.AddObserver (NSWindow.DidResignKeyNotification, notification => Runtime.RunInMainThread (() => {
 				var other = (NSWindow)notification.Object;
 
 				if (notification.Object == Window) {
@@ -252,8 +252,8 @@ void Initialize ()
 							LostFocus (this, null);
 					}
 				}
-			}));
-			NSNotificationCenter.DefaultCenter.AddObserver (NSWindow.DidResizeNotification, notification => Runtime.RunInMainThread (() => {
+			})));
+			MacPlatformService.AllObservers.Add (NSNotificationCenter.DefaultCenter.AddObserver (NSWindow.DidResizeNotification, notification => Runtime.RunInMainThread (() => {
 				var other = (NSWindow)notification.Object;
 				if (notification.Object == Window) {
 					if (IsFirstResponderOfWindow (Window)) {
@@ -261,7 +261,7 @@ void Initialize ()
 							LostFocus (this, null);
 					}
 				}
-			}));
+			})));
 		}
 
 		bool IsFirstResponderOfWindow (NSWindow window)
diff --git a/main/src/addins/MacPlatform/MainToolbar/SelectorView.cs b/main/src/addins/MacPlatform/MainToolbar/SelectorView.cs
index 3fb5e464b6e..3617e8fc153 100644
--- a/main/src/addins/MacPlatform/MainToolbar/SelectorView.cs
+++ b/main/src/addins/MacPlatform/MainToolbar/SelectorView.cs
@@ -788,8 +788,8 @@ public override void ViewDidMoveToWindow ()
 			{
 				base.ViewDidMoveToWindow ();
 
-				NSNotificationCenter.DefaultCenter.AddObserver (NSWindow.DidChangeBackingPropertiesNotification,
-				                                                notification => Runtime.RunInMainThread ((Action) RealignTexts));
+				MacPlatformService.AllObservers.Add (NSNotificationCenter.DefaultCenter.AddObserver (NSWindow.DidChangeBackingPropertiesNotification,
+				                                                notification => Runtime.RunInMainThread ((Action) RealignTexts)));
 				RealignTexts ();
 			}
 
diff --git a/main/src/addins/MacPlatform/ScreenMonitor.cs b/main/src/addins/MacPlatform/ScreenMonitor.cs
index ce0361ce905..3e176a73f45 100644
--- a/main/src/addins/MacPlatform/ScreenMonitor.cs
+++ b/main/src/addins/MacPlatform/ScreenMonitor.cs
@@ -56,9 +56,9 @@ public static class ScreenMonitor
 		static ScreenMonitor ()
 		{
 			screenToGdk = UpdateScreenLayout ();
-			NSNotificationCenter.DefaultCenter.AddObserver (NSApplication.DidChangeScreenParametersNotification, (obj) => {
+			MacPlatformService.AllObservers.Add (NSNotificationCenter.DefaultCenter.AddObserver (NSApplication.DidChangeScreenParametersNotification, (obj) => {
 				screenToGdk = UpdateScreenLayout ();
-			});
+			}));
 		}
 
 		public static CGPoint GdkPointForNSScreen (NSScreen screen)