窗口全屏切换 从退出全屏时肯定变为Normal改成变为进入全屏前的状态(即 也可能进入Maximized状态)

src/Ursa/Controls/TitleBar/CaptionButtons.cs

@@ -25,7 +25,11 @@ public class CaptionButtons: Avalonia.Controls.Chrome.CaptionButtons
     private Button? _fullScreenButton;
     
     private IDisposable? _visibilityDisposable;
-    
+
+    /// <summary>
+    /// <20>л<EFBFBD><D0BB><EFBFBD><EFBFBD><EFBFBD>ȫ<EFBFBD><C8AB>ǰ <20><><EFBFBD>ڵ<EFBFBD>״̬
+    /// </summary>
+    private WindowState? _oldWindowState;
     protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
     {
         _closeButton = e.NameScope.Get<Button>(PART_CloseButton);
@@ -43,6 +47,21 @@ public class CaptionButtons: Avalonia.Controls.Chrome.CaptionButtons
         UpdateVisibility();
     }
 
+    protected override void OnToggleFullScreen()
+    {
+        if (HostWindow != null)
+        {
+            if (HostWindow.WindowState != WindowState.FullScreen)
+            {
+                _oldWindowState = HostWindow.WindowState;
+                HostWindow.WindowState = WindowState.FullScreen;
+            }
+            else
+            {
+                HostWindow.WindowState = _oldWindowState.HasValue ? _oldWindowState.Value : WindowState.Normal;
+            }
+        }
+    }
     public override void Attach(Window hostWindow)
     {
         base.Attach(hostWindow);