Don't apply styling in TopLevel ctor.

Applying styling in the constructor isn't a good idea as demonstrated by #8549..

Instead apply styling when showing a window, or if it's needed call `ApplyStyling` manually, e.g. in unit tests.

Fixes #8549

src/Avalonia.Base/PropertyStore/ValueStore.cs

@@ -610,8 +610,7 @@ namespace Avalonia.PropertyStore
 
         private int InsertFrame(ValueFrame frame)
         {
-            // Uncomment this line when #8549 is fixed.
-            //Debug.Assert(!_frames.Contains(frame));
+            Debug.Assert(!_frames.Contains(frame));
 
             var index = BinarySearchFrame(frame.Priority);
             _frames.Insert(index, frame);

src/Avalonia.Controls/TopLevel.cs

@@ -182,8 +182,6 @@ namespace Avalonia.Controls
                 _globalStyles.GlobalStylesRemoved += ((IStyleHost)this).StylesRemoved;
             }
 
-            ApplyStyling();
-
             ClientSize = impl.ClientSize;
             FrameSize = impl.FrameSize;
             

src/Avalonia.Controls/Window.cs

@@ -647,6 +647,7 @@ namespace Avalonia.Controls
             RaiseEvent(new RoutedEventArgs(WindowOpenedEvent));
 
             EnsureInitialized();
+            ApplyStyling();
             IsVisible = true;
 
             var initialSize = new Size(
@@ -726,6 +727,7 @@ namespace Avalonia.Controls
             RaiseEvent(new RoutedEventArgs(WindowOpenedEvent));
 
             EnsureInitialized();
+            ApplyStyling();
             IsVisible = true;
 
             var initialSize = new Size(

src/Avalonia.Controls/WindowBase.cs

@@ -149,6 +149,7 @@ namespace Avalonia.Controls
             try
             {
                 EnsureInitialized();
+                ApplyStyling();
                 IsVisible = true;
 
                 if (!_hasExecutedInitialLayoutPass)

tests/Avalonia.Controls.UnitTests/AutoCompleteBoxTests.cs

@@ -1056,6 +1056,7 @@ namespace Avalonia.Controls.UnitTests
                 control.Items = CreateSimpleStringArray();
                 TextBox textBox = GetTextBox(control);
                 var window = new Window {Content = control};
+                window.ApplyStyling();
                 window.ApplyTemplate();
                 window.Presenter.ApplyTemplate();
                 Dispatcher.UIThread.RunJobs();

tests/Avalonia.Controls.UnitTests/ContextMenuTests.cs

@@ -29,6 +29,7 @@ namespace Avalonia.Controls.UnitTests
                 };
 
                 var window = new Window { Content = target };
+                window.ApplyStyling();
                 window.ApplyTemplate();
                 window.Presenter.ApplyTemplate();
 
@@ -61,6 +62,7 @@ namespace Avalonia.Controls.UnitTests
                 };
 
                 var window = new Window { Content = target };
+                window.ApplyStyling();
                 window.ApplyTemplate();
                 window.Presenter.ApplyTemplate();
 
@@ -130,6 +132,7 @@ namespace Avalonia.Controls.UnitTests
                 };
 
                 var window = new Window { Content = target };
+                window.ApplyStyling();
                 window.ApplyTemplate();
                 window.Presenter.ApplyTemplate();
 
@@ -158,6 +161,7 @@ namespace Avalonia.Controls.UnitTests
                 };
 
                 var window = new Window { Content = target };
+                window.ApplyStyling();
                 window.ApplyTemplate();
                 window.Presenter.ApplyTemplate();
 
@@ -186,6 +190,7 @@ namespace Avalonia.Controls.UnitTests
                 };
 
                 var window = new Window { Content = target };
+                window.ApplyStyling();
                 window.ApplyTemplate();
                 window.Presenter.ApplyTemplate();
 
@@ -207,6 +212,7 @@ namespace Avalonia.Controls.UnitTests
                 };
 
                 var window = new Window { Content = target };
+                window.ApplyStyling();
                 window.ApplyTemplate();
                 window.Presenter.ApplyTemplate();
 
@@ -390,7 +396,8 @@ namespace Avalonia.Controls.UnitTests
 
                 var sp = new StackPanel { Children = { target1, target2 } };
                 var window = new Window { Content = sp };
-                
+
+                window.ApplyStyling();
                 window.ApplyTemplate();
                 window.Presenter.ApplyTemplate();
 
@@ -594,6 +601,7 @@ namespace Avalonia.Controls.UnitTests
             windowImpl.Setup(x => x.CreateRenderer(It.IsAny<IRenderRoot>())).Returns(renderer.Object);
 
             var w = new Window(windowImpl.Object) { Content = content };
+            w.ApplyStyling();
             w.ApplyTemplate();
             w.Presenter.ApplyTemplate();
             return w;

tests/Avalonia.Controls.UnitTests/MenuItemTests.cs

@@ -193,6 +193,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new MenuItem();
                 var contextMenu = new ContextMenu { Items = new AvaloniaList<MenuItem> { target } };
                 var window = new Window { Content = new Panel { ContextMenu = contextMenu } };
+                window.ApplyStyling();
                 window.ApplyTemplate();
                 window.Presenter.ApplyTemplate();
                 
@@ -232,6 +233,7 @@ namespace Avalonia.Controls.UnitTests
                 var flyout = new MenuFlyout { Items = new AvaloniaList<MenuItem> { target } };
                 var button = new Button { Flyout = flyout };
                 var window = new Window { Content = button };
+                window.ApplyStyling();
                 window.ApplyTemplate();
                 window.Presenter.ApplyTemplate();
                 
@@ -271,6 +273,7 @@ namespace Avalonia.Controls.UnitTests
                 var parentMenuItem = new MenuItem { Items = new AvaloniaList<MenuItem> { target } };
                 var contextMenu = new ContextMenu { Items = new AvaloniaList<MenuItem> { parentMenuItem } };
                 var window = new Window { Content = new Panel { ContextMenu = contextMenu } };
+                window.ApplyStyling();
                 window.ApplyTemplate();
                 window.Presenter.ApplyTemplate();
                 contextMenu.Open();

tests/Avalonia.Controls.UnitTests/NumericUpDownTests.cs

@@ -50,6 +50,7 @@ namespace Avalonia.Controls.UnitTests
                 var control = CreateControl();
                 TextBox textBox = GetTextBox(control);
                 var window = new Window { Content = control };
+                window.ApplyStyling();
                 window.ApplyTemplate();
                 window.Presenter.ApplyTemplate();
                 Dispatcher.UIThread.RunJobs();

tests/Avalonia.Controls.UnitTests/Primitives/PopupRootTests.cs

@@ -51,6 +51,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 };
                 window.Content = target;
 
+                window.ApplyStyling();
                 window.ApplyTemplate();
                 window.Presenter.ApplyTemplate();
                 target.ApplyTemplate();
@@ -177,6 +178,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 };
                 window.Content = target;
 
+                window.ApplyStyling();
                 window.ApplyTemplate();
                 window.Presenter.ApplyTemplate();
                 target.ApplyTemplate();

tests/Avalonia.Controls.UnitTests/Primitives/PopupTests.cs

@@ -569,6 +569,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 windowImpl.Setup(x => x.CreateRenderer(It.IsAny<IRenderRoot>())).Returns(renderer.Object);
 
                 var window = new Window(windowImpl.Object);
+                window.ApplyStyling();
                 window.ApplyTemplate();
 
                 var target = new Popup() 
@@ -1090,6 +1091,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
         private Window PreparedWindow(object content = null)
         {
             var w = new Window { Content = content };
+            w.ApplyStyling();
             w.ApplyTemplate();
             return w;
         }

tests/Avalonia.Controls.UnitTests/ToolTipTests.cs

@@ -51,6 +51,7 @@ namespace Avalonia.Controls.UnitTests
 
                 window.Content = panel;
 
+                window.ApplyStyling();
                 window.ApplyTemplate();
                 window.Presenter.ApplyTemplate();
 
@@ -114,6 +115,7 @@ namespace Avalonia.Controls.UnitTests
 
                 window.Content = target;
 
+                window.ApplyStyling();
                 window.ApplyTemplate();
                 window.Presenter.ApplyTemplate();
 
@@ -140,6 +142,7 @@ namespace Avalonia.Controls.UnitTests
 
                 window.Content = target;
 
+                window.ApplyStyling();
                 window.ApplyTemplate();
                 window.Presenter.ApplyTemplate();
 
@@ -183,6 +186,7 @@ namespace Avalonia.Controls.UnitTests
 
                 window.Content = target;
 
+                window.ApplyStyling();
                 window.ApplyTemplate();
                 window.Presenter.ApplyTemplate();
 
@@ -215,6 +219,7 @@ namespace Avalonia.Controls.UnitTests
 
                 window.Content = decorator;
 
+                window.ApplyStyling();
                 window.ApplyTemplate();
                 window.Presenter.ApplyTemplate();
 
@@ -237,6 +242,7 @@ namespace Avalonia.Controls.UnitTests
 
                 window.Content = decorator;
 
+                window.ApplyStyling();
                 window.ApplyTemplate();
                 window.Presenter.ApplyTemplate();
 
@@ -261,6 +267,7 @@ namespace Avalonia.Controls.UnitTests
 
                 window.Content = decorator;
 
+                window.ApplyStyling();
                 window.ApplyTemplate();
                 window.Presenter.ApplyTemplate();
 
@@ -286,6 +293,7 @@ namespace Avalonia.Controls.UnitTests
 
                 window.Content = target;
 
+                window.ApplyStyling();
                 window.ApplyTemplate();
                 window.Presenter.ApplyTemplate();
 

tests/Avalonia.Markup.Xaml.UnitTests/Xaml/BasicTests.cs

@@ -720,7 +720,12 @@ namespace Avalonia.Markup.Xaml.UnitTests.Xaml
                 //ensure binding is set and operational first
                 Assert.Equal(100.0, tracker.Tag);
 
-                Assert.Equal("EndInit 0", tracker.Order.Last());
+                // EndInit should be second-to-last operation, as last operation will be
+                // caused by styling being applied on EndInit.
+                Assert.Equal("EndInit 0", tracker.Order[tracker.Order.Count - 2]);
+
+                // Caused by styling.
+                Assert.Equal("Property Foreground Changed", tracker.Order[tracker.Order.Count - 1]);
             }
         }