diff --git a/Nerfed.Runtime/Engine.cs b/Nerfed.Runtime/Engine.cs
index 7a6a21b..da76aa9 100644
--- a/Nerfed.Runtime/Engine.cs
+++ b/Nerfed.Runtime/Engine.cs
@@ -19,7 +19,6 @@ public static class Engine
     private static Stopwatch gameTimer;
     private static long previousTicks = 0;
     private static TimeSpan accumulatedUpdateTime = TimeSpan.Zero;
-
     private static TimeSpan accumulatedDrawTime = TimeSpan.Zero;
 
     // must be a power of 2 so we can do a bitmask optimization when checking worst case
@@ -65,6 +64,10 @@ internal static void Run(string[] args)
             throw new Exception("Failed to claim window");
         }
 
+        MainWindow.OnCloseEvent += (w) => {
+            quit = true;
+        };
+
         AudioDevice = new AudioDevice();
 
         Controller = new Gui.GuiController(GraphicsDevice, MainWindow, Color.DarkOliveGreen);
diff --git a/Nerfed.Runtime/Gui/GuiController.cs b/Nerfed.Runtime/Gui/GuiController.cs
index 5b278de..f8e36ff 100644
--- a/Nerfed.Runtime/Gui/GuiController.cs
+++ b/Nerfed.Runtime/Gui/GuiController.cs
@@ -37,7 +37,8 @@ internal class GuiController : IDisposable
     private readonly Shader imGuiFragmentShader;
     private readonly Sampler imGuiSampler;
     private readonly GuiTextureStorage textureStorage = new GuiTextureStorage();
-    private readonly Dictionary<Window, GCHandle> windows = new Dictionary<Window, GCHandle>(16);
+    private readonly Dictionary<Window, GCHandle> windowToHandle = new Dictionary<Window, GCHandle>(16);
+    private readonly Dictionary<ImGuiViewportPtr, Window> imguiToWindow = new Dictionary<ImGuiViewportPtr, Window>(16);
 
     private Texture fontTexture = null;
     private uint vertexCount = 0;
@@ -49,7 +50,6 @@ internal class GuiController : IDisposable
     public GuiController(GraphicsDevice graphicsDevice, Window mainWindow, Color clearColor, ImGuiConfigFlags configFlags = ImGuiConfigFlags.NavEnableKeyboard | ImGuiConfigFlags.DockingEnable | ImGuiConfigFlags.ViewportsEnable)
     {
         this.mainWindow = mainWindow;
-        this.graphicsDevice = graphicsDevice;
         this.clearColor = clearColor;
 
         resourceUploader = new ResourceUploader(graphicsDevice);
@@ -100,7 +100,6 @@ public GuiController(GraphicsDevice graphicsDevice, Window mainWindow, Color cle
         BuildFontAtlas();
 
         io.ConfigFlags = configFlags;
-        //io.MouseDrawCursor = true;
 
         if (!OperatingSystem.IsWindows())
         {
@@ -167,11 +166,6 @@ public void Update(float deltaTime)
 
         OnGui?.Invoke();
 
-        {   // Debug
-            ImGuiIOPtr io = ImGui.GetIO();
-            ImGui.Text($"mouse pos: {io.MousePos}");
-        }
-
         ImGui.EndFrame();
     }
 
@@ -557,21 +551,21 @@ private void CreateWindow(ImGuiViewportPtr vp)
 
     private void DestroyWindow(ImGuiViewportPtr vp)
     {
-        if (vp.PlatformUserData == IntPtr.Zero) return;
+        //Window window = (Window)GCHandle.FromIntPtr(vp.PlatformUserData).Target;
 
-        Window window = (Window)GCHandle.FromIntPtr(vp.PlatformUserData).Target;
-        graphicsDevice.UnclaimWindow(window);
-
-        if (windows.TryGetValue(window, out GCHandle handle))
+        if(imguiToWindow.TryGetValue(vp, out Window window))
         {
-            handle.Free();
-            windows.Remove(window);
+            graphicsDevice.UnclaimWindow(window);
+
+            if (windowToHandle.TryGetValue(window, out GCHandle handle))
+            {
+                handle.Free();
+                windowToHandle.Remove(window);
+            }
+
+            imguiToWindow.Remove(vp);
+            window.Dispose();
         }
-
-        //graphicsDevice.Wait();
-        window.Dispose();
-
-        vp.PlatformUserData = IntPtr.Zero;
     }
 
     private void AddWindow(Window window, ImGuiViewportPtr vp, GCHandle handle)
@@ -592,14 +586,12 @@ private void AddWindow(Window window, ImGuiViewportPtr vp, GCHandle handle)
             for (int i = 0; i < platformIO.Viewports.Capacity; i++)
             {
                 ImGuiViewportPtr vp = platformIO.Viewports[i];
-                if(win == (Window)GCHandle.FromIntPtr(vp.PlatformUserData).Target)
-                {
-                    DestroyWindow(vp);
-                }
+                DestroyWindow(vp);
             }
         };
 
-        windows.Add(window, handle);
+        windowToHandle.Add(window, handle);
+        imguiToWindow.Add(vp, window);
     }
 
     private void ShowWindow(ImGuiViewportPtr vp)
@@ -697,7 +689,7 @@ public void Dispose()
         imGuiSampler?.Dispose();
         resourceUploader?.Dispose();
 
-        foreach (KeyValuePair<Window, GCHandle> window in windows)
+        foreach (KeyValuePair<Window, GCHandle> window in windowToHandle)
         {
             if (window.Key == mainWindow) continue;
 
@@ -705,6 +697,7 @@ public void Dispose()
             window.Key.Dispose();
             window.Value.Free();
         }
-        windows.Clear();
+        windowToHandle.Clear();
+        imguiToWindow.Clear();
     }
 }
\ No newline at end of file
diff --git a/Nerfed.Runtime/Window/Window.cs b/Nerfed.Runtime/Window/Window.cs
index 56ca056..d9f5cb3 100644
--- a/Nerfed.Runtime/Window/Window.cs
+++ b/Nerfed.Runtime/Window/Window.cs
@@ -136,9 +136,9 @@ private void ProcessMovedChangedEvent(ref SDL.SDL_WindowEvent ev)
 
     private void ProcessCloseEvent(ref SDL.SDL_WindowEvent ev)
 	{
+		OnCloseEvent?.Invoke(this);
 		Engine.GraphicsDevice.UnclaimWindow(this);
 		Dispose();
-		OnCloseEvent?.Invoke(this);
 	}
 
 	/// <summary>