From a56903d3ade19924d5ff407a1883213f88dfd321 Mon Sep 17 00:00:00 2001
From: Ari Vuollet <ari.vuollet@goat.moe>
Date: Tue, 25 Aug 2026 22:33:39 +0300
Subject: [PATCH] Fix client-side decorations in borderless editor game window
 on launch

---
 .../GUI/Docking/FloatWindowDockPanel.cs       | 42 +++++++++++++------
 Source/Editor/Windows/GameWindow.cs           |  7 ++++
 2 files changed, 37 insertions(+), 12 deletions(-)

diff --git a/Source/Editor/GUI/Docking/FloatWindowDockPanel.cs b/Source/Editor/GUI/Docking/FloatWindowDockPanel.cs
index b47d76bdd..788631daa 100644
--- a/Source/Editor/GUI/Docking/FloatWindowDockPanel.cs
+++ b/Source/Editor/GUI/Docking/FloatWindowDockPanel.cs
@@ -65,6 +65,31 @@ namespace FlaxEditor.GUI.Docking
         /// </summary>
         public bool IsDragging { get; internal set; }
 
+        /// <summary>
+        /// Shows client-side window decorations around this panel.
+        /// </summary>
+        public bool ShowDecorations
+        {
+            get;
+            set
+            {
+                if (value == field)
+                    return;
+                field = value;
+                if (value)
+                {
+                    var decorations = Parent.AddChild(new FloatWindowDecorations(this));
+                    decorations.SetAnchorPreset(AnchorPresets.HorizontalStretchTop, false);
+                }
+                else
+                {
+                    var decorations = Parent.GetChild<FloatWindowDecorations>();
+                    if (decorations != null)
+                        decorations.Dispose();
+                }
+            }
+        } = false;
+
         /// <summary>
         /// Initializes a new instance of the <see cref="FloatWindowDockPanel"/> class.
         /// </summary>
@@ -82,11 +107,7 @@ namespace FlaxEditor.GUI.Docking
             _window.Window.Closing += OnClosing;
             _window.Window.LeftButtonHit += OnLeftButtonHit;
 
-            if (Utilities.Utils.UseCustomWindowDecorations())
-            {
-                var decorations = Parent.AddChild(new FloatWindowDecorations(this));
-                decorations.SetAnchorPreset(AnchorPresets.HorizontalStretchTop, false);
-            }
+            ShowDecorations = Utilities.Utils.UseCustomWindowDecorations();
         }
 
         /// <inheritdoc />
@@ -94,13 +115,10 @@ namespace FlaxEditor.GUI.Docking
         {
             base.PerformLayoutBeforeChildren();
 
-            var decorations = Parent.GetChild<FloatWindowDecorations>();
-            if (decorations != null)
-            {
-                // Apply offset for the title bar
-                foreach (var child in Children)
-                    child.Bounds = child.Bounds with { Y = decorations.Height, Height = Parent.Height - decorations.Height };
-            }
+            // Apply offset for the title bar
+            var decorationsHeight = Parent.GetChild<FloatWindowDecorations>()?.Height ?? 0;
+            foreach (var child in Children)
+                child.Bounds = child.Bounds with { Y = decorationsHeight, Height = Parent.Height - decorationsHeight };
         }
 
         /// <summary>
diff --git a/Source/Editor/Windows/GameWindow.cs b/Source/Editor/Windows/GameWindow.cs
index 8c3793627..9419fbb51 100644
--- a/Source/Editor/Windows/GameWindow.cs
+++ b/Source/Editor/Windows/GameWindow.cs
@@ -5,6 +5,7 @@ using System.Collections.Generic;
 using System.Xml;
 using FlaxEditor.Gizmo;
 using FlaxEditor.GUI.ContextMenu;
+using FlaxEditor.GUI.Docking;
 using FlaxEditor.GUI.Input;
 using FlaxEditor.Modules;
 using FlaxEditor.Options;
@@ -331,6 +332,9 @@ namespace FlaxEditor.Windows
                 {
                     IsFloating = true;
                     var rootWindow = RootWindow;
+                    var floatWin = rootWindow.GetChild<FloatWindowDockPanel>();
+                    if (floatWin != null && floatWin.ShowDecorations)
+                        floatWin.ShowDecorations = false;
                     var monitorBounds = Platform.GetMonitorBounds(rootWindow.RootWindow.Window.ClientPosition);
                     rootWindow.Window.Position = monitorBounds.Location;
                     rootWindow.Window.SetBorderless(true);
@@ -338,6 +342,9 @@ namespace FlaxEditor.Windows
                 }
                 else
                 {
+                    var floatWin = RootWindow.GetChild<FloatWindowDockPanel>();
+                    if (floatWin != null && !floatWin.ShowDecorations && Utilities.Utils.UseCustomWindowDecorations())
+                        floatWin.ShowDecorations = true;
                     IsFloating = false;
                 }
             }