ToolTip should use Popup internally + fix Popups not closing when placement target is closed

src/Avalonia.Controls/ContextMenu.cs

@@ -324,11 +324,7 @@ private void Open(Control control, Control placementTarget, PlacementMode placem
                 _popup.KeyUp += PopupKeyUp;
             }
 
-            if (_popup.Parent != control)
-            {
-                ((ISetLogicalParent)_popup).SetParent(null);
-                ((ISetLogicalParent)_popup).SetParent(control);
-            }
+            _popup.SetPopupParent(control);
 
             _popup.Placement = placement;
 
@@ -383,7 +379,7 @@ private void PopupClosed(object? sender, EventArgs e)
 
             if (_attachedControls is null || _attachedControls.Count == 0)
             {
-                ((ISetLogicalParent)_popup!).SetParent(null);
+                _popup!.SetPopupParent(null);
             }
 
             RaiseEvent(new RoutedEventArgs

src/Avalonia.Controls/Flyouts/PopupFlyoutBase.cs

@@ -189,7 +189,8 @@ protected virtual bool HideCore(bool canCancel = true)
             IsOpen = false;
             Popup.IsOpen = false;
 
-            ((ISetLogicalParent)Popup).SetParent(null);
+            Popup.PlacementTarget = null;
+            Popup.SetPopupParent(null);
 
             // Ensure this isn't active
             _transientDisposable?.Dispose();
@@ -205,6 +206,9 @@ protected virtual bool HideCore(bool canCancel = true)
 
             OnClosed();
 
+            // Set to null after all other events.
+            Target = null;
+
             return true;
         }
 
@@ -228,17 +232,8 @@ protected virtual bool ShowAtCore(Control placementTarget, bool showAtPointer =
                 }
             }
 
-            if (Popup.Parent != null && Popup.Parent != placementTarget)
-            {
-                ((ISetLogicalParent)Popup).SetParent(null);
-            }
-
-            if (Popup.Parent == null || Popup.PlacementTarget != placementTarget)
-            {
-                Popup.PlacementTarget = Target = placementTarget;
-                ((ISetLogicalParent)Popup).SetParent(placementTarget);
-                Popup.TemplatedParent = placementTarget.TemplatedParent;
-            }
+            Popup.PlacementTarget = Target = placementTarget;
+            Popup.SetPopupParent(placementTarget);
 
             if (Popup.Child == null)
             {

src/Avalonia.Controls/Primitives/OverlayPopupHost.cs

@@ -3,6 +3,7 @@
 using Avalonia.Controls.Primitives.PopupPositioning;
 using Avalonia.Interactivity;
 using Avalonia.Media;
+using Avalonia.Metadata;
 using Avalonia.Threading;
 using Avalonia.VisualTree;
 
@@ -135,7 +136,9 @@ void IManagedPopupPositionerPopup.MoveAndResize(Point devicePoint, Size virtualS
         }
 
         double IManagedPopupPositionerPopup.Scaling => 1;
-
+
+        // TODO12: mark PrivateAPI or internal.
+        [Unstable("PopupHost is consireded an internal API. Use Popup or any Popup-based controls (Flyout, Tooltip) instead.")]
         public static IPopupHost CreatePopupHost(Visual target, IAvaloniaDependencyResolver? dependencyResolver)
         {
             if (TopLevel.GetTopLevel(target) is { } topLevel && topLevel.PlatformImpl?.CreatePopup() is { } popupImpl)

src/Avalonia.Controls/Primitives/Popup.cs

@@ -580,6 +580,23 @@ protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs chang
             }
         }
 
+        /// <summary>
+        /// Helper method to set popup's styling and templated parent.
+        /// </summary>
+        internal void SetPopupParent(Control? newParent)
+        {
+            if (Parent != null && Parent != newParent)
+            {
+                ((ISetLogicalParent)this).SetParent(null);
+            }
+
+            if (Parent == null || PlacementTarget != newParent)
+            {
+                ((ISetLogicalParent)this).SetParent(newParent);
+                TemplatedParent = newParent?.TemplatedParent;
+            }
+        }
+
         private void UpdateHostPosition(IPopupHost popupHost, Control placementTarget)
         {
             popupHost.ConfigurePosition(

src/Avalonia.Controls/ToolTip.cs

@@ -1,4 +1,5 @@
 using System;
+using System.ComponentModel;
 using Avalonia.Controls.Diagnostics;
 using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
@@ -79,19 +80,16 @@ public class ToolTip : ContentControl, IPopupHostProvider
         internal static readonly AttachedProperty<ToolTip?> ToolTipProperty =
             AvaloniaProperty.RegisterAttached<ToolTip, Control, ToolTip?>("ToolTip");
 
-        private IPopupHost? _popupHost;
+        private Popup? _popup;
         private Action<IPopupHost?>? _popupHostChangedHandler;
+        private CompositeDisposable? _subscriptions;
 
         /// <summary>
         /// Initializes static members of the <see cref="ToolTip"/> class.
         /// </summary>
         static ToolTip()
         {
             IsOpenProperty.Changed.Subscribe(IsOpenChanged);
-
-            HorizontalOffsetProperty.Changed.Subscribe(RecalculatePositionOnPropertyChanged);
-            VerticalOffsetProperty.Changed.Subscribe(RecalculatePositionOnPropertyChanged);
-            PlacementProperty.Changed.Subscribe(RecalculatePositionOnPropertyChanged);
         }
 
         internal Control? AdornedControl { get; private set; }
@@ -309,69 +307,64 @@ private static void IsOpenChanged(AvaloniaPropertyChangedEventArgs e)
             }
         }
 
-        private static void RecalculatePositionOnPropertyChanged(AvaloniaPropertyChangedEventArgs args)
-        {
-            var control = (Control)args.Sender;
-            var tooltip = control.GetValue(ToolTipProperty);
-            if (tooltip == null)
-            {
-                return;
-            }
+        IPopupHost? IPopupHostProvider.PopupHost => _popup?.Host;
 
-            tooltip.RecalculatePosition(control);
-        }
-
-        IPopupHost? IPopupHostProvider.PopupHost => _popupHost;
-
-        internal IPopupHost? PopupHost => _popupHost;
+        internal IPopupHost? PopupHost => _popup?.Host;
 
         event Action<IPopupHost?>? IPopupHostProvider.PopupHostChanged 
         { 
             add => _popupHostChangedHandler += value; 
             remove => _popupHostChangedHandler -= value;
         }
 
-        internal void RecalculatePosition(Control control)
-        {
-            _popupHost?.ConfigurePosition(control, GetPlacement(control), new Point(GetHorizontalOffset(control), GetVerticalOffset(control)));
-        }
-
         private void Open(Control control)
         {
             Close();
+
+            if (_popup is null)
+            {
+                _popup = new Popup();
+                _popup.Child = this;
+                _popup.WindowManagerAddShadowHint = false;
 
-            _popupHost = OverlayPopupHost.CreatePopupHost(control, null);
-            _popupHost.SetChild(this);
-            ((ISetLogicalParent)_popupHost).SetParent(control);
-            ApplyTemplatedParent(this, control.TemplatedParent);
+                _popup.Opened += OnPopupOpened;
+                _popup.Closed += OnPopupClosed;
+            }
 
-            _popupHost.ConfigurePosition(control, GetPlacement(control),
-                new Point(GetHorizontalOffset(control), GetVerticalOffset(control)));
+            _subscriptions = new CompositeDisposable(new[]
+            {
+                _popup.Bind(Popup.HorizontalOffsetProperty, control.GetBindingObservable(HorizontalOffsetProperty)),
+                _popup.Bind(Popup.VerticalOffsetProperty, control.GetBindingObservable(VerticalOffsetProperty)),
+                _popup.Bind(Popup.PlacementProperty, control.GetBindingObservable(PlacementProperty))
+            });
 
-            WindowManagerAddShadowHintChanged(_popupHost, false);
+            _popup.PlacementTarget = control;
+            _popup.SetPopupParent(control);
 
-            _popupHost.Show();
-            _popupHostChangedHandler?.Invoke(_popupHost);
+            _popup.IsOpen = true;
         }
 
         private void Close()
         {
-            if (_popupHost != null)
+            _subscriptions?.Dispose();
+
+            if (_popup is not null)
             {
-                _popupHost.SetChild(null);
-                _popupHost.Dispose();
-                _popupHost = null;
-                _popupHostChangedHandler?.Invoke(null);
-                Closed?.Invoke(this, EventArgs.Empty);
+                _popup.IsOpen = false;
+                _popup.SetPopupParent(null);
+                _popup.PlacementTarget = null;
             }
         }
 
-        private void WindowManagerAddShadowHintChanged(IPopupHost host, bool hint)
+        private void OnPopupClosed(object? sender, EventArgs e)
         {
-            if (host is PopupRoot pr)
-            {
-                pr.WindowManagerAddShadowHint = hint;
-            }
+            _popupHostChangedHandler?.Invoke(null);
+            Closed?.Invoke(this, EventArgs.Empty);
+        }
+
+        private void OnPopupOpened(object? sender, EventArgs e)
+        {
+            _popupHostChangedHandler?.Invoke(((Popup)sender!).Host);
         }
 
         private void UpdatePseudoClasses(bool newValue)

src/Avalonia.Controls/ToolTipService.cs

@@ -22,8 +22,7 @@ public ToolTipService(IInputManager inputManager)
             _subscriptions = new CompositeDisposable(
                 inputManager.Process.Subscribe(InputManager_OnProcess),
                 ToolTip.ServiceEnabledProperty.Changed.Subscribe(ServiceEnabledChanged),
-                ToolTip.TipProperty.Changed.Subscribe(TipChanged),
-                ToolTip.IsOpenProperty.Changed.Subscribe(TipOpenChanged));
+                ToolTip.TipProperty.Changed.Subscribe(TipChanged));
         }
 
         public void Dispose()
@@ -122,30 +121,6 @@ private void TipChanged(AvaloniaPropertyChangedEventArgs e)
             }
         }
 
-        private void TipOpenChanged(AvaloniaPropertyChangedEventArgs e)
-        {
-            var control = (Control)e.Sender;
-
-            if (e.OldValue is false && e.NewValue is true)
-            {
-                control.DetachedFromVisualTree += ControlDetaching;
-                control.EffectiveViewportChanged += ControlEffectiveViewportChanged;
-            }
-            else if (e.OldValue is true && e.NewValue is false)
-            {
-                control.DetachedFromVisualTree -= ControlDetaching;
-                control.EffectiveViewportChanged -= ControlEffectiveViewportChanged;
-            }
-        }
-
-        private void ControlDetaching(object? sender, VisualTreeAttachmentEventArgs e)
-        {
-            var control = (Control)sender!;
-            control.DetachedFromVisualTree -= ControlDetaching;
-            control.EffectiveViewportChanged -= ControlEffectiveViewportChanged;
-            Close(control);
-        }
-
         private void OnTipControlChanged(Control? oldValue, Control? newValue)
         {
             StopTimer();
@@ -184,13 +159,6 @@ private void OnTipControlChanged(Control? oldValue, Control? newValue)
             }
         }
 
-        private void ControlEffectiveViewportChanged(object? sender, Layout.EffectiveViewportChangedEventArgs e)
-        {
-            var control = (Control)sender!;
-            var toolTip = control.GetValue(ToolTip.ToolTipProperty);
-            toolTip?.RecalculatePosition(control);
-        }
-
         private void ToolTipClosed(object? sender, EventArgs e)
         {
             _lastTipCloseTime = DateTime.UtcNow.Ticks;