diff --git a/HAModHelper.GamePlugin/Base/Base.GamePlugin.cs b/HAModHelper.GamePlugin/Base/Base.GamePlugin.cs
index e999a2d..c9252dd 100644
--- a/HAModHelper.GamePlugin/Base/Base.GamePlugin.cs
+++ b/HAModHelper.GamePlugin/Base/Base.GamePlugin.cs
@@ -1,6 +1,7 @@
 using System.Diagnostics;
 using HAModHelper.GamePlugin.Items.Systems;
 using HAModHelper.GamePlugin.Perks.Systems;
+using HAModHelper.GamePlugin.Gui.Systems;
 using HAModHelper.GamePlugin.Dialogue.Systems;
 using HAModHelper.GamePlugin.Core.Debug;
 using System.Net;
@@ -84,9 +85,14 @@ public override void Load()
             Log.LogInfo($"[HAMH] Initialized CraftingInjectionManager in {stopwatch4.ElapsedMilliseconds}ms.");
 
             var stopwatch5 = Stopwatch.StartNew();
-            DialogueManager.Instance.Initialize();
+            WindowManager.Instance.Initialize();
             stopwatch5.Stop();
-            Log.LogInfo($"[HAMH] Initialized DialogueManager in {stopwatch5.ElapsedMilliseconds}ms.");
+            Log.LogInfo($"[HAMH] Initialized WindowManager in {stopwatch5.ElapsedMilliseconds}ms.");
+
+            var stopwatch6 = Stopwatch.StartNew();
+            DialogueManager.Instance.Initialize();
+            stopwatch6.Stop();
+            Log.LogInfo($"[HAMH] Initialized DialogueManager in {stopwatch6.ElapsedMilliseconds}ms.");
 
             //var stopwatch3 = Stopwatch.StartNew();
             //UniverseLibConfig uvlconfig = new UniverseLibConfig
diff --git a/HAModHelper.GamePlugin/Gui/Gui.Events.cs b/HAModHelper.GamePlugin/Gui/Gui.Events.cs
new file mode 100644
index 0000000..6a4b065
--- /dev/null
+++ b/HAModHelper.GamePlugin/Gui/Gui.Events.cs
@@ -0,0 +1,15 @@
+using HAModHelper.GamePlugin.Base.Events;
+
+namespace HAModHelper.GamePlugin.Gui.Events;
+
+public class CustomScreenOpenedEvent : BaseEvent
+{
+    public string ScreenId { get; }
+    public CustomScreenOpenedEvent(string screenId) => ScreenId = screenId;
+}
+
+public class CustomScreenClosedEvent : BaseEvent
+{
+    public string ScreenId { get; }
+    public CustomScreenClosedEvent(string screenId) => ScreenId = screenId;
+}
diff --git a/HAModHelper.GamePlugin/Gui/Gui.Interfaces.cs b/HAModHelper.GamePlugin/Gui/Gui.Interfaces.cs
new file mode 100644
index 0000000..1f353e4
--- /dev/null
+++ b/HAModHelper.GamePlugin/Gui/Gui.Interfaces.cs
@@ -0,0 +1,57 @@
+using UnityEngine;
+
+namespace HAModHelper.GamePlugin.Gui.Interfaces;
+
+public interface IWindowPrefabsControl
+{
+    Transform? GuiCanvasTransform { get; }
+
+    GameObject? GetScreen(string screenId);
+
+    GameObject? GetObject(string screenId, string objName);
+
+    bool HasScreen(string screenId);
+
+    /// <summary>Register an already-instantiated screen so the game's own GetScreen/GetObject calls find it too.</summary>
+    void RegisterInstantiated(string screenId, GameObject instance);
+
+    void DestroyScreen(string screenId);
+}
+
+// runtime adapter that wraps the real game WindowPrefabsControl/WindowControl
+public class UnityWindowPrefabsControl : IWindowPrefabsControl
+{
+    private readonly WindowPrefabsControl _wpc;
+    private readonly WindowControl _wc;
+
+    public UnityWindowPrefabsControl(WindowPrefabsControl wpc, WindowControl wc)
+    {
+        _wpc = wpc;
+        _wc = wc;
+    }
+
+    public Transform? GuiCanvasTransform => _wc.gui_canvas != null ? _wc.gui_canvas.transform : null;
+
+    public GameObject? GetScreen(string screenId) => _wpc.GetScreen(screenId);
+
+    public GameObject? GetObject(string screenId, string objName) => _wpc.GetObject(screenId, objName);
+
+    public bool HasScreen(string screenId) => _wpc.prefab_screens_instantiated.ContainsKey(screenId);
+
+    public void RegisterInstantiated(string screenId, GameObject instance)
+    {
+        _wpc.prefab_screens_instantiated[screenId] = instance;
+    }
+
+    public void DestroyScreen(string screenId) => _wpc.DestroyScreen(screenId);
+}
+
+public class DebugNoLoadWindowPrefabsControl : IWindowPrefabsControl
+{
+    public Transform? GuiCanvasTransform => null;
+    public GameObject? GetScreen(string screenId) => null;
+    public GameObject? GetObject(string screenId, string objName) => null;
+    public bool HasScreen(string screenId) => false;
+    public void RegisterInstantiated(string screenId, GameObject instance) { }
+    public void DestroyScreen(string screenId) { }
+}
diff --git a/HAModHelper.GamePlugin/Gui/Gui.Systems.cs b/HAModHelper.GamePlugin/Gui/Gui.Systems.cs
new file mode 100644
index 0000000..b6d4971
--- /dev/null
+++ b/HAModHelper.GamePlugin/Gui/Gui.Systems.cs
@@ -0,0 +1,148 @@
+using HAModHelper.GamePlugin.Core;
+using HAModHelper.GamePlugin.Base.Events;
+using HAModHelper.GamePlugin.Gui.Events;
+using HAModHelper.GamePlugin.Gui.Interfaces;
+using UnityEngine;
+using Object = UnityEngine.Object;
+
+namespace HAModHelper.GamePlugin.Gui.Systems;
+
+/// <summary>
+/// Lets mods register their own AssetBundle-backed UI screens and show/hide them under
+/// the game's main GUI canvas. Registered screens are written into
+/// <c>WindowPrefabsControl.prefab_screens_instantiated</c> so the game's own
+/// <c>GetScreen</c>/<c>GetObject</c>/<c>DestroyScreen</c> calls keep working on them too —
+/// mirrors how <see cref="Items.Systems.WorldPrefabManager"/> injects custom world prefabs.
+/// </summary>
+public sealed class WindowManager
+{
+    public static WindowManager Instance { get; } = new();
+
+    private sealed class ScreenEntry
+    {
+        public required AssetBundle Bundle;
+        public required string AssetName;
+        public GameObject? Cache;
+    }
+
+    private readonly Dictionary<string, ScreenEntry> _screens = new();
+
+    // TEST-ONLY: Spoof a fake WindowPrefabsControl for tests
+    public IWindowPrefabsControl? DebugWindowPrefabsControlSource { get; set; }
+
+    private WindowManager() { }
+
+    private IWindowPrefabsControl? GetControl()
+    {
+        if (DebugWindowPrefabsControlSource?.GetType() == typeof(DebugNoLoadWindowPrefabsControl))
+            return null;
+
+        if (DebugWindowPrefabsControlSource != null)
+            return DebugWindowPrefabsControlSource;
+
+        try
+        {
+            var wpc = WindowPrefabsControl.Instance;
+            var wc = WindowControl.Instance;
+            if (wpc == null || wc == null) return null;
+            var proxy = new UnityWindowPrefabsControl(wpc, wc);
+            return proxy.GuiCanvasTransform == null ? null : proxy;
+        }
+        catch (Exception)
+        {
+            return null;
+        }
+    }
+
+    /// <summary>TEST-ONLY: Reset system state.</summary>
+    public void Reset()
+    {
+        _screens.Clear();
+        DebugWindowPrefabsControlSource = null;
+    }
+
+    /// <summary>Initialize the window manager (called on game start).</summary>
+    public void Initialize()
+    {
+    }
+
+    /// <summary>
+    /// Register a custom screen prefab.
+    /// </summary>
+    /// <param name="screenId">Unique id for the screen, used with <see cref="ShowScreen"/> etc.</param>
+    /// <param name="bundle">AssetBundle that contains the prefab. Keep a static reference
+    ///   in your plugin so the native backing is never freed.</param>
+    /// <param name="assetName">Name of the prefab asset inside the bundle.</param>
+    public void RegisterScreen(string screenId, AssetBundle bundle, string assetName)
+    {
+        _screens[screenId] = new ScreenEntry { Bundle = bundle, AssetName = assetName };
+    }
+
+    /// <summary>
+    /// Instantiate (first call) or re-show a registered custom screen, parented under the
+    /// game's main GUI canvas. Returns null if the screen isn't registered or the game's
+    /// window system isn't loaded yet.
+    /// </summary>
+    public GameObject? ShowScreen(string screenId)
+    {
+        var control = GetControl();
+        if (control == null)
+        {
+            try { HAMHMod.Logger.LogInfo($"[HAMH] WindowPrefabsControl not ready, can't show screen {screenId}"); } catch { }
+            return null;
+        }
+
+        var existing = control.GetScreen(screenId);
+        if (existing != null)
+        {
+            existing.SetActive(true);
+            EventBus.Instance.Fire(new CustomScreenOpenedEvent(screenId));
+            return existing;
+        }
+
+        if (!_screens.TryGetValue(screenId, out var entry))
+        {
+            try { HAMHMod.Logger.LogInfo($"[HAMH] No custom screen registered for {screenId}"); } catch { }
+            return null;
+        }
+
+        if (entry.Cache == null)
+        {
+            var asset = entry.Bundle.LoadAsset(entry.AssetName);
+            if (asset == null) return null;
+            entry.Cache = asset.Cast<GameObject>();
+        }
+
+        var instance = Object.Instantiate(entry.Cache, control.GuiCanvasTransform);
+        instance.SetActive(true);
+        control.RegisterInstantiated(screenId, instance);
+
+        EventBus.Instance.Fire(new CustomScreenOpenedEvent(screenId));
+        return instance;
+    }
+
+    /// <summary>Hide a shown custom (or base-game) screen without destroying it.</summary>
+    public bool HideScreen(string screenId)
+    {
+        var existing = GetControl()?.GetScreen(screenId);
+        if (existing == null) return false;
+
+        existing.SetActive(false);
+        EventBus.Instance.Fire(new CustomScreenClosedEvent(screenId));
+        return true;
+    }
+
+    /// <summary>Destroy a shown custom (or base-game) screen entirely.</summary>
+    public bool DestroyScreen(string screenId)
+    {
+        var control = GetControl();
+        if (control == null || !control.HasScreen(screenId)) return false;
+
+        control.DestroyScreen(screenId);
+        EventBus.Instance.Fire(new CustomScreenClosedEvent(screenId));
+        return true;
+    }
+
+    /// <summary>Look up a child object inside a screen (custom or base-game) by name.</summary>
+    public GameObject? GetObject(string screenId, string objName) => GetControl()?.GetObject(screenId, objName);
+}