From d8eb12fab0dd1adf9305edeb31f5a7685f8b9960 Mon Sep 17 00:00:00 2001
From: Zhang Dian <54255897+zdpcdt@users.noreply.github.com>
Date: Sat, 21 Mar 2026 19:55:54 +0800
Subject: [PATCH] feat: preserve window state before entering fullscreen mode.

---
 .../Chrome/WindowDrawnDecorations.cs            | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/src/Avalonia.Controls/Chrome/WindowDrawnDecorations.cs b/src/Avalonia.Controls/Chrome/WindowDrawnDecorations.cs
index 48847b5f59..179389a3bb 100644
--- a/src/Avalonia.Controls/Chrome/WindowDrawnDecorations.cs
+++ b/src/Avalonia.Controls/Chrome/WindowDrawnDecorations.cs
@@ -138,6 +138,7 @@ public class WindowDrawnDecorations : StyledElement
     private IDisposable? _windowSubscriptions;
     private Window? _hostWindow;
     private double _titleBarHeightOverride = -1;
+    private WindowState _stateBeforeFullScreen = WindowState.Normal;
 
     /// <summary>
     /// Raised when any property affecting the effective geometry changes
@@ -523,10 +524,18 @@ public class WindowDrawnDecorations : StyledElement
     private void OnFullScreenButtonClick(object? sender, Interactivity.RoutedEventArgs e)
     {
         if (_hostWindow != null)
-            _hostWindow.WindowState = _hostWindow.WindowState == WindowState.FullScreen
-                ? WindowState.Normal
-                : WindowState.FullScreen;
-        e.Handled = true;
+        {
+            if (_hostWindow.WindowState != WindowState.FullScreen)
+            {
+                _stateBeforeFullScreen = _hostWindow.WindowState;
+                _hostWindow.WindowState = WindowState.FullScreen;
+            }
+            else
+            {
+                _hostWindow.WindowState = _stateBeforeFullScreen;
+            }
+            e.Handled = true;
+        }
     }
 
     private void UpdateMaximizeButtonState()