diff --git a/GlitchyEditor/src/Assets/AssetHierarchy.bf b/GlitchyEditor/src/Assets/AssetHierarchy.bf
index 5d13be3..5d93e50 100644
--- a/GlitchyEditor/src/Assets/AssetHierarchy.bf
+++ b/GlitchyEditor/src/Assets/AssetHierarchy.bf
@@ -6,6 +6,7 @@ using System.Collections;
 using System.IO;
 using System.Linq;
 using GlitchyEngine.Content;
+using GlitchyEditor.Multithreading;
 
 namespace GlitchyEditor.Assets;
 
@@ -662,6 +663,41 @@ class AssetHierarchy
 		Combine
  	}
 
+	/*public Result<BackgroundTask> CopyExternFileToNodeBackground(TreeNode<AssetNode> targetDirectory, String sourcePath, OverwriteMode overwrite)
+	{
+		if (!targetDirectory->IsDirectory)
+			return .Err;
+		
+		FileInfo sourceInfo = scope FileInfo(sourcePath);
+
+		if (!sourceInfo.Exists)
+			return .Err;
+
+		CopyBackgroundTask copyTask = new CopyBackgroundTask(sourcePath, targetDirectory->Path);
+
+		EditorApp.Instance.BackgroundTaskManager.StartBackgroundTask(copyTask);
+
+		return copyTask;
+	}*/
+
+	public Result<BackgroundTask> CopyExternFilesToNodeBackground(TreeNode<AssetNode> targetDirectory, List<String> sourcePaths, OverwriteMode overwrite)
+	{
+		if (!targetDirectory->IsDirectory)
+			return .Err;
+		
+		/*FileInfo sourceInfo = scope FileInfo(sourcePath);
+
+		if (!sourceInfo.Exists)
+			return .Err;*/
+
+		CopyBackgroundTask copyTask = new CopyBackgroundTask(sourcePaths, targetDirectory->Path);
+		copyTask.DeleteWhenStopped = true;
+
+		EditorApp.Instance.BackgroundTaskManager.StartBackgroundTask(copyTask);
+
+		return copyTask;
+	}
+
 	public Result<void, CopyError> CopyExternFileToNode(TreeNode<AssetNode> targetDirectory, String sourcePath, OverwriteMode overwrite)
 	{
 		if (!targetDirectory->IsDirectory)
@@ -691,7 +727,7 @@ class AssetHierarchy
 				case .KeepBoth:
 					String fileExtension = scope .();
 					Path.GetExtension(targetPath, fileExtension);
-					FindFreePath(targetDirectory->Path, fileName.Substring(0..<^fileExtension.Length), fileExtension, targetPath..Clear());
+					Path.FindFreePath(targetDirectory->Path, fileName.Substring(0..<^fileExtension.Length), fileExtension, targetPath..Clear());
 				case .Overwrite:
 					forceOverwrite = true;
 				default:
@@ -709,7 +745,7 @@ class AssetHierarchy
 				case .KeepBoth:
 					String fileExtension = scope .();
 					Path.GetExtension(targetPath, fileExtension);
-					FindFreePath(targetDirectory->Path, fileName.Substring(0..<^fileExtension.Length), fileExtension, targetPath..Clear());
+					Path.FindFreePath(targetDirectory->Path, fileName.Substring(0..<^fileExtension.Length), fileExtension, targetPath..Clear());
 				case .Overwrite:
 					forceOverwrite = true;
 				default:
@@ -722,25 +758,4 @@ class AssetHierarchy
 
 		return .Ok;
 	}
-
-	public void FindFreePath(StringView directory, StringView wantedName, StringView fileExtension, String outFreePath)
-	{
-		int fileNumber = 0;
-
-		String currentFileName = scope $"{wantedName}{fileExtension}";
-		while (true)
-		{
-			Path.Combine(outFreePath..Clear(), directory, currentFileName);
-			
-			FileInfo targetInfo = scope FileInfo(outFreePath);
-
-			if (!targetInfo.Exists)
-			{
-				break;
-			}
-
-			fileNumber++;
-			currentFileName..Clear().AppendF($"{wantedName} ({fileNumber}){fileExtension}");
-		}
-	}
 }
diff --git a/GlitchyEditor/src/Assets/Editors/MaterialEditor.bf b/GlitchyEditor/src/Assets/Editors/MaterialEditor.bf
index 9da249c..e4d0aa8 100644
--- a/GlitchyEditor/src/Assets/Editors/MaterialEditor.bf
+++ b/GlitchyEditor/src/Assets/Editors/MaterialEditor.bf
@@ -52,6 +52,8 @@ class MaterialEditor
 				if (DrawLockButton(bufferVariable.Flags.HasFlag(.Locked)) && !readOnly)
 				{
 					bufferVariable.[Friend]_flags ^= .Locked;
+					// Also mark as dirty so we update our children!
+					bufferVariable.[Friend]_flags |= .Dirty;
 				}
 
 				ImGui.SameLine();
@@ -165,6 +167,8 @@ class MaterialEditor
 				if (DrawLockButton(texture.Flags.HasFlag(.Locked)) && !readOnly)
 				{
 					texture.Flags ^= .Locked;
+					// Also mark as dirty so we update our children!
+					texture.Flags |= .Dirty;
 				}
 
 				ImGui.SameLine();
diff --git a/GlitchyEditor/src/EditWindows/ContentBrowserWindow.bf b/GlitchyEditor/src/EditWindows/ContentBrowserWindow.bf
index ea0e3f0..288316b 100644
--- a/GlitchyEditor/src/EditWindows/ContentBrowserWindow.bf
+++ b/GlitchyEditor/src/EditWindows/ContentBrowserWindow.bf
@@ -608,12 +608,14 @@ namespace GlitchyEditor.EditWindows
 
 							List<String> droppedFiles = (.)Internal.UnsafeCastToObject(*(void**)peekPayload.Data);
 
-							for (String path in droppedFiles)
+							_manager.AssetHierarchy.CopyExternFilesToNodeBackground(dropTarget, droppedFiles, .None);
+
+							/*for (String path in droppedFiles)
 							{
 								Log.EngineLogger.Info($"Dropping file {path}");
 								
-								_manager.AssetHierarchy.CopyExternFileToNode(dropTarget, path, .None);
-							}
+								//_manager.AssetHierarchy.CopyExternFileToNodeBackground(dropTarget, path, .None);
+							}*/
 						}
 						else
 						{
diff --git a/GlitchyEditor/src/EditorApp.bf b/GlitchyEditor/src/EditorApp.bf
index f6dc2e2..d9015f9 100644
--- a/GlitchyEditor/src/EditorApp.bf
+++ b/GlitchyEditor/src/EditorApp.bf
@@ -7,6 +7,8 @@ using GlitchyEditor.Assets.Processors;
 using GlitchyEditor.Assets.Exporters;
 using DirectX.Common;
 using GlitchyEditor.Platform.Windows;
+using GlitchyEditor.Multithreading;
+using System.Threading;
 
 namespace GlitchyEditor
 {
@@ -14,22 +16,31 @@ namespace GlitchyEditor
 	{
 		EditorContentManager _contentManager;
 
+		public new static EditorApp Instance => Application.Instance as EditorApp;
+
+		private append BackgroundTaskManager _backgroundTaskManager = .();
+
+		public BackgroundTaskManager BackgroundTaskManager => _backgroundTaskManager;
+		
 		public this(String[] args)
 		{
 			Log.ClientLogger = new EditorLogger();
 			Log.EngineLogger = new EditorLogger() { IsEngineLogger = true };
-			
+
+			_backgroundTaskManager.Init();
+
 			// TODO: Windows only
 			HResult result = OleInitialize(null);
 			Log.EngineLogger.Assert(result case .S_OK);
 
 			PushLayer(new EditorLayer(args, _contentManager));
-
 		}
 
 		public ~this()
 		{
 			OleUninitialize();
+
+			_backgroundTaskManager.Deinit();
 		}
 
 		protected override IContentManager InitContentManager()
diff --git a/GlitchyEditor/src/EditorLayer.bf b/GlitchyEditor/src/EditorLayer.bf
index 9ecefca..d992846 100644
--- a/GlitchyEditor/src/EditorLayer.bf
+++ b/GlitchyEditor/src/EditorLayer.bf
@@ -1243,6 +1243,8 @@ namespace GlitchyEditor
 			}
 #endif
 
+			EditorApp.Instance.BackgroundTaskManager.ImGuiRender();
+
 			_editor.SceneViewportWindow.RenderTarget = _editorViewportTarget;
 			_editor.GameViewportWindow.RenderTarget = _gameViewportTarget;
 
diff --git a/GlitchyEditor/src/Multithreading/BackgroundTask.bf b/GlitchyEditor/src/Multithreading/BackgroundTask.bf
new file mode 100644
index 0000000..f3b75e9
--- /dev/null
+++ b/GlitchyEditor/src/Multithreading/BackgroundTask.bf
@@ -0,0 +1,76 @@
+using System;
+using System.IO;
+using System.Threading;
+using System.Collections;
+using System.Diagnostics;
+using ImGui;
+
+namespace GlitchyEditor.Multithreading;
+
+using internal GlitchyEditor.Multithreading;
+
+abstract class BackgroundTask
+{
+	internal BackgroundTaskList _list;
+	internal BackgroundTask _previous;
+	internal BackgroundTask _next;
+
+	internal BackgroundTaskManager _taskManager;
+
+	public enum RunState
+	{
+		Ready,
+		Blocked,
+		Paused,
+		Running,
+		Aborted,
+		Finished
+	}
+	 
+	public enum RunResult
+	{
+		/// The task gives up it's runtime, but has to run again.
+		Continue,
+		/// The task gives up it's runtime, because it cannot continue without user intervention through the UI.
+		Pause,
+		/// The task finished and wont run again.
+		Finished,
+		/// The operation was aborted, the task will not run again.
+		Abort
+	}
+
+    public RunState State { get; internal set; } = .Ready;
+
+	public bool Ready => State == .Ready;
+	public bool Paused => State == .Paused;
+	public bool Blocked => State == .Blocked;
+	public bool Running => State == .Running;
+	public bool Aborted => State == .Aborted;
+	public bool Finished => State == .Finished;
+
+	public bool Ended => Finished || Aborted;
+
+	public bool DeleteWhenStopped { get; set; }
+
+	public abstract RunResult Run();
+
+	public abstract void OnRenderPopup();
+
+	public void Continue()
+	{
+		_taskManager.ContinueTask(this);
+	}
+
+	public void Pause()
+	{
+		if (State == .Ready || State == .Running)
+		{
+			State = .Paused;
+		}
+	}
+
+	public void Abort()
+	{
+		_taskManager.AbortTask(this);
+	}
+}
diff --git a/GlitchyEditor/src/Multithreading/BackgroundTaskList.bf b/GlitchyEditor/src/Multithreading/BackgroundTaskList.bf
new file mode 100644
index 0000000..c535e09
--- /dev/null
+++ b/GlitchyEditor/src/Multithreading/BackgroundTaskList.bf
@@ -0,0 +1,422 @@
+using System;
+using System.Diagnostics;
+
+namespace GlitchyEditor.Multithreading;
+
+using internal GlitchyEditor.Multithreading;
+
+class BackgroundTaskList
+{
+	BackgroundTask _sentinel = new BackgroundTask()
+	{
+		public override BackgroundTask.RunResult Run() => .Finished;
+		public override void OnRenderPopup() { }
+		_next = _,
+		_previous = _,
+		_list = this
+	} ~ delete _;
+
+	private int _count;
+
+	public BackgroundTask First => _sentinel._next == _sentinel ? null : _sentinel._next;
+	public BackgroundTask Last => _sentinel._previous == _sentinel ? null : _sentinel._previous;
+	public BackgroundTask End => _sentinel;
+
+	public int Count => _count;
+
+	private void InsertBefore(BackgroundTask item, BackgroundTask beforeNode)
+	{
+		item._next = beforeNode;
+		item._previous = beforeNode._previous;
+		item._next._previous = item;
+		item._previous._next = item;
+
+		item._list = this;
+
+		_count++;
+
+		Validate();
+	}
+
+	public void AddFirst(BackgroundTask item)
+	{
+		if (item._list != null)
+			item._list.Remove(item, false);
+
+		InsertBefore(item, _sentinel._next);
+	}
+
+	public void AddLast(BackgroundTask item)
+	{
+		if (item._list != null)
+			item._list.Remove(item, false);
+
+		InsertBefore(item, _sentinel);
+	}
+
+	public void Clear()
+	{
+		Clear(false);
+	}
+
+	public void Clear(bool deleteElements)
+	{
+		BackgroundTask task = _sentinel._next;
+
+		while (task != _sentinel)
+		{
+			BackgroundTask nextTask = task._next;
+
+			UnlinkElement(task);
+			if (deleteElements)
+				delete task;
+
+			task = nextTask;
+		}
+
+		_sentinel._next = _sentinel._previous = _sentinel;
+
+		_count = 0;
+
+		Validate();
+	}
+
+	private void UnlinkElement(BackgroundTask element)
+	{
+		element._next = null;
+		element._previous = null;
+		element._list = null;
+	}
+
+	public bool Contains(BackgroundTask item)
+	{
+		return item._list == this;
+	}
+
+	public bool Remove(BackgroundTask item)
+	{
+		return Remove(item, false);
+	}
+
+	public bool Remove(BackgroundTask item, bool deleteElement)
+	{
+		if (item._list != this)
+			return false;
+
+		item._previous._next = item._next;
+		item._next._previous = item._previous;
+
+		UnlinkElement(item);
+
+		if (deleteElement)
+			delete item;
+
+		_count--;
+
+		Validate();
+
+		return true;
+	}
+
+	public Result<BackgroundTask> TryPopFront()
+	{
+		if (_sentinel._next == _sentinel)
+			return .Err;
+
+		BackgroundTask first = _sentinel._next;
+
+		Remove(first, false);
+
+		return first;
+	}
+
+	public Result<BackgroundTask> TryPopBack()
+	{
+		if (_sentinel._previous == _sentinel)
+			return .Err;
+
+		BackgroundTask first = _sentinel._previous;
+
+		Remove(first, false);
+
+		return first;
+	}
+
+	internal void Validate()
+	{
+		BackgroundTask task = _sentinel._next;
+
+		int visitedNodes = 0;
+
+		while (task != _sentinel)
+		{
+			visitedNodes++;
+
+			Debug.Assert(visitedNodes <= Count);
+			Debug.Assert(task._list == this);
+
+			BackgroundTask nextTask = task._next;
+
+			Debug.Assert(nextTask._previous == task);
+			task = nextTask;
+		}
+
+		Debug.Assert(visitedNodes == Count);
+	}
+}
+
+class BackgroundTaskListTests
+{
+	// Stub implementation
+	class BackgroundTask : GlitchyEditor.Multithreading.BackgroundTask
+	{
+		public override BackgroundTask.RunResult Run()
+		{
+			return default;
+		}
+
+		public override void OnRenderPopup()
+		{
+
+		}
+	}
+
+    static void TestBasicOperations()
+    {
+        Debug.WriteLine("🧪 Testing Basic Operations...");
+        
+        var list1 = scope BackgroundTaskList();
+        
+        var task1 = scope BackgroundTask();
+        var task2 = scope BackgroundTask();
+        
+        // Test AddFirst
+        list1.AddFirst(task1);
+        Debug.Assert(list1.Count == 1);
+        Debug.Assert(task1._list == list1);
+        Debug.Assert(list1.Contains(task1));
+		list1.Validate();
+        
+        // Test AddLast
+        list1.AddLast(task2);
+        Debug.Assert(list1.Count == 2);
+        Debug.Assert(task2._list == list1);
+        Debug.Assert(list1.Contains(task2));
+		list1.Validate();
+        
+        // Test Remove
+        list1.Remove(task1);
+        Debug.Assert(list1.Count == 1);
+        Debug.Assert(task1._list == null);
+        Debug.Assert(!list1.Contains(task1));
+        Debug.Assert(list1.Contains(task2));
+		list1.Validate();
+        
+        Debug.WriteLine("✅ Basic Operations passed!");
+    }
+    
+    static void TestAutoRemoveFromOldList()
+    {
+        Debug.WriteLine("🧪 Testing Auto-Remove from Old List...");
+        
+        var list1 = scope BackgroundTaskList();
+        var list2 = scope BackgroundTaskList();
+        
+        var task = scope BackgroundTask();
+        
+        // Add to list1
+        list1.AddFirst(task);
+        Debug.Assert(list1.Count == 1);
+        Debug.Assert(list2.Count == 0);
+        Debug.Assert(task._list == list1);
+		list1.Validate();
+		list2.Validate();
+        
+        // Add to list2 - should remove from list1
+        list2.AddLast(task);
+        Debug.Assert(list1.Count == 0);
+        Debug.Assert(list2.Count == 1);
+        Debug.Assert(task._list == list2);
+        Debug.Assert(!list1.Contains(task));
+        Debug.Assert(list2.Contains(task));
+		list1.Validate();
+		list2.Validate();
+        
+        // add to list1 again, should be removed from list2
+        list1.AddFirst(task);
+        Debug.Assert(list1.Count == 1);
+        Debug.Assert(list2.Count == 0);
+        Debug.Assert(task._list == list1);
+		list1.Validate();
+		list2.Validate();
+        
+        Debug.WriteLine("✅ Auto-Remove passed!");
+    }
+    
+    static void TestTryPopFront()
+    {
+        Debug.WriteLine("🧪 Testing TryPopFront...");
+        
+        var list = scope BackgroundTaskList();
+        
+        // Test empty list
+        let emptyResult = list.TryPopFront();
+        Debug.Assert(emptyResult == .Err);
+		list.Validate();
+        
+        var task1 = scope BackgroundTask();
+        var task2 = scope BackgroundTask();
+        var task3 = scope BackgroundTask();
+        
+        // Add three elements
+        list.AddLast(task1);
+		list.Validate();
+        list.AddLast(task2);
+		list.Validate();
+        list.AddLast(task3);
+		list.Validate();
+        Debug.Assert(list.Count == 3);
+        
+        // Pop first element
+        let pop1 = list.TryPopFront();
+        Debug.Assert(pop1 == .Ok(task1));
+        Debug.Assert(list.Count == 2);
+        Debug.Assert(task1._list == null);
+		list.Validate();
+        
+        // Pop second element
+        let pop2 = list.TryPopFront();
+        Debug.Assert(pop2 == .Ok(task2));
+        Debug.Assert(list.Count == 1);
+        Debug.Assert(task2._list == null);
+		list.Validate();
+        
+        // Pop third element
+        let pop3 = list.TryPopFront();
+        Debug.Assert(pop3 == .Ok(task3));
+        Debug.Assert(list.Count == 0);
+        Debug.Assert(task3._list == null);
+		list.Validate();
+        
+        // Pop on now empty list
+        let pop4 = list.TryPopFront();
+        Debug.Assert(pop4 == .Err);
+		list.Validate();
+        
+        Debug.WriteLine("✅ TryPopFront passed!");
+    }
+    
+    /*static void TestIterator()
+    {
+        Debug.WriteLine("🧪 Testing Iterator...");
+        
+        var list = scope BackgroundTaskList();
+        var tasks = scope BackgroundTask*[5];
+        
+        for (int i = 0; i < tasks.Count; i++)
+        {
+            tasks[i] = new BackgroundTask();
+            list.AddLast(tasks[i]);
+        }
+        defer { for (var t in tasks) delete t; }
+        
+        // Teste Iterator
+        int count = 0;
+        for (var task in list)
+        {
+            Debug.Assert(task == tasks[count]);
+            count++;
+        }
+        Debug.Assert(count == 5);
+        
+        Debug.WriteLine("✅ Iterator passed!");
+    }*/
+    
+    static void TestClear()
+    {
+        Debug.WriteLine("🧪 Testing Clear...");
+        
+        var list = scope BackgroundTaskList();
+
+        var task1 = scope BackgroundTask();
+        var task2 = scope BackgroundTask();
+        var task3 = scope BackgroundTask();
+        
+        list.AddLast(task1);
+		list.Validate();
+        list.AddLast(task2);
+		list.Validate();
+        list.AddLast(task3);
+		list.Validate();
+        Debug.Assert(list.Count == 3);
+        
+        // Clear sollte task1 und task3 löschen, aber nicht task2
+        list.Clear();
+        Debug.Assert(list.Count == 0);
+		list.Validate();
+        
+        Debug.WriteLine("✅ Clear passed!");
+    }
+    
+    static void TestComplexScenario()
+    {
+		// Simulate processing queues.
+        Debug.WriteLine("🧪 Testing Complex Scenario...");
+        
+        var pending = scope BackgroundTaskList();
+        var processing = scope BackgroundTaskList();
+        var completed = scope BackgroundTaskList();
+
+		// Add to pending
+        var tasks = scope BackgroundTask[10];
+        for (int i = 0; i < tasks.Count; i++)
+        {
+            tasks[i] = scope:: BackgroundTask();
+            pending.AddLast(tasks[i]);
+			pending.Validate();
+        }
+        
+        // Move from pending to processing
+        while (true)
+        {
+            let result = pending.TryPopFront();
+            if (result == .Err) break;
+            
+            let task = result.Value;
+            processing.AddLast(task);
+			processing.Validate();
+        }
+        
+        Debug.Assert(pending.Count == 0);
+        Debug.Assert(processing.Count == 10);
+        
+		// Move to completed
+        while (true)
+        {
+            let result = processing.TryPopFront();
+            if (result == .Err) break;
+            
+            completed.AddLast(result.Value);
+			completed.Validate();
+        }
+        
+        Debug.Assert(processing.Count == 0);
+        Debug.Assert(completed.Count == 10);
+        
+        Debug.WriteLine("✅ Complex Scenario passed!");
+    }
+    
+    public static void RunTests()
+    {
+        Debug.WriteLine("🚀 Starting BackgroundTaskList Tests...\n");
+        
+        TestBasicOperations();
+        TestAutoRemoveFromOldList();
+        TestTryPopFront();
+        //TestIterator();
+        TestClear();
+        TestComplexScenario();
+        
+        Debug.WriteLine("\n🎉 All tests passed!");
+    }
+}
\ No newline at end of file
diff --git a/GlitchyEditor/src/Multithreading/BackgroundTaskManager.bf b/GlitchyEditor/src/Multithreading/BackgroundTaskManager.bf
new file mode 100644
index 0000000..b4702ff
--- /dev/null
+++ b/GlitchyEditor/src/Multithreading/BackgroundTaskManager.bf
@@ -0,0 +1,216 @@
+using System;
+using System.Threading;
+using System.Collections;
+using GlitchyEngine;
+using GlitchyEngine.Collections;
+
+namespace GlitchyEditor.Multithreading;
+
+using internal GlitchyEditor.Multithreading;
+
+// This would go nicely with some light weight threading!
+class BackgroundTaskManager
+{
+	private Thread _workerThread;
+
+	private bool _run;
+
+	private BackgroundTask _runningTask;
+	private append BackgroundTaskList _readyQueue = .();
+	private append BackgroundTaskList _waitingTasks = .();
+	private append Monitor _queueLock = .();
+
+	public void Init()
+	{
+		_run = true;
+		_workerThread = new Thread(new => WorkerLoop);
+		_workerThread.Start();
+	}
+	
+	public void Deinit()
+	{
+		_run = false;
+
+		// TODO: Delete jobs if necessary
+		// TODO: Danger if thread is deadlocked.
+		_workerThread.Join();
+	}
+
+	private void WorkerLoop()
+	{
+		while (_run)
+		{
+			Result<BackgroundTask> nextRunningTask = .Err;
+
+			using (_queueLock.Enter())
+			{
+				nextRunningTask = _readyQueue.TryPopFront();
+			}
+
+			if (nextRunningTask case .Ok(let task))
+			{
+				_runningTask = task;
+				_runningTask.State = .Running;
+				BackgroundTask.RunResult runResult = task.Run();
+				_runningTask = null;
+
+				switch (runResult)
+				{
+				case .Continue:
+					task.State = .Ready;
+					using (_queueLock.Enter())
+					{
+						_readyQueue.AddLast(task);
+					}
+				case .Pause:
+					task.State = .Paused;
+					using (_queueLock.Enter())
+					{
+						_waitingTasks.AddLast(task);
+					}
+				case .Finished:
+					task.State = .Finished;
+		
+					if (task.DeleteWhenStopped)
+					{
+						delete task;
+					}
+				case .Abort:
+					task.State = .Aborted;
+
+					if (task.DeleteWhenStopped)
+					{
+						delete task;
+					}
+				}
+			}
+            else
+			{
+				Thread.Sleep(10);
+			}
+		}
+	}
+
+	public Result<void> StartBackgroundTask(BackgroundTask task)
+	{
+		if (task._taskManager != null)
+		{
+			Log.EngineLogger.Error("Task is already managed by a taskmanager.");
+			return .Err;
+		}
+
+		if (task.State == .Running || task.State == .Aborted)
+		{
+			Log.EngineLogger.Error("Task State illegal. (Did it already run?)");
+			return .Err;
+		}
+
+		task._taskManager = this;
+
+		using (_queueLock.Enter())
+		{
+			if (task.State == .Ready)
+				_readyQueue.AddLast(task);
+			else
+				_waitingTasks.AddLast(task);
+		}
+
+		return .Ok;
+	}
+
+	internal void ContinueTask(BackgroundTask task)
+	{
+		Log.EngineLogger.AssertDebug(task._taskManager == this);
+		Log.EngineLogger.AssertDebug(!task.Ended);
+
+		Application.Instance.InvokeOnMainThread(new () =>
+			{
+				if (task.State == .Paused)
+				{
+					task.State = .Ready;
+		
+					using (_queueLock.Enter())
+					{
+						Log.EngineLogger.AssertDebug(!_readyQueue.Contains(task));
+						// We assume this was a user interaction so this task will get some priority.
+						_readyQueue.AddFirst(task);
+					}
+				}
+				return true;
+			});
+	}
+	
+	internal void Pause(BackgroundTask task)
+	{
+		Log.EngineLogger.AssertDebug(task._taskManager == this);
+		Log.EngineLogger.AssertDebug(!task.Ended);
+		
+		Application.Instance.InvokeOnMainThread(new () =>
+			{
+				if (task.State == .Ready)
+				{
+					task.State = .Ready;
+
+					using (_queueLock.Enter())
+					{
+						Log.EngineLogger.AssertDebug(!_waitingTasks.Contains(task));
+						_waitingTasks.AddLast(task);
+					}
+				}
+				return true;
+			});
+	}
+	
+	internal void AbortTask(BackgroundTask task)
+	{
+		Log.EngineLogger.AssertDebug(task._taskManager == this);
+		Log.EngineLogger.AssertDebug(!task.Ended);
+		
+		Application.Instance.InvokeOnMainThread(new () =>
+			{
+				if (task.State != .Aborted)
+				{
+					task.State = .Aborted;
+
+					using (_queueLock.Enter())
+					{
+						_waitingTasks.Remove(task);
+					}
+
+					if (task.DeleteWhenStopped)
+					{
+						delete task;
+					}
+				}
+				return true;
+			});
+	}
+
+	public void ImGuiRender()
+	{
+		using (_queueLock.Enter())
+		{
+			_runningTask?.OnRenderPopup();
+
+			BackgroundTask task = _readyQueue.First;
+
+			while (task != null && task != _readyQueue.End)
+			{
+				Log.EngineLogger.Assert(task._list == _readyQueue); 
+
+				task.OnRenderPopup();
+				task = task._next;
+			}
+			
+			BackgroundTask wtask = _waitingTasks.First;
+			
+			while (wtask != null && wtask != _waitingTasks.End)
+			{
+				Log.EngineLogger.Assert(wtask._list == _waitingTasks); 
+
+				wtask.OnRenderPopup();
+				wtask = wtask._next;
+			}
+		}
+	}
+}
\ No newline at end of file
diff --git a/GlitchyEditor/src/Multithreading/CopyBackgroundTask.bf b/GlitchyEditor/src/Multithreading/CopyBackgroundTask.bf
new file mode 100644
index 0000000..6d21a6f
--- /dev/null
+++ b/GlitchyEditor/src/Multithreading/CopyBackgroundTask.bf
@@ -0,0 +1,320 @@
+using System;
+using System.IO;
+using System.Collections;
+using System.Diagnostics;
+using ImGui;
+
+namespace GlitchyEditor.Multithreading;
+
+class CopyBackgroundTask : BackgroundTask
+{
+	private List<String> _sourcePath ~ {ClearAndDeleteItems!(_); delete:append _;};
+	private String _targetDirectoryPath ~ delete:append _;
+
+	private int _totalEntriesToCopy;
+	private append Queue<CopyInfo> _pathsToCopy = .() ~ ClearAndDeleteItems!(_);
+	private append Queue<String> _scanQueue = .() ~ ClearAndDeleteItems!(_);
+	
+	private enum OverwriteMode
+	{
+		None,
+		OverwriteFile = 1,
+		KeepBoth = 2,
+		CombineDirectories = 4,
+		Skip = 8
+	}
+
+	private OverwriteMode _nextFileMode;
+	private OverwriteMode _allFilesMode;
+
+	private OverwriteMode CurrentFileMode => _nextFileMode | _allFilesMode;
+
+	private class CopyInfo
+	{
+		public String SourcePath ~ delete:append _;
+		public String TargetPath ~ delete:append _;
+		public OverwriteMode OverwriteMode;
+
+		[AllowAppend]
+		public this(StringView sourcePath, StringView targetPath, OverwriteMode overwriteMode)
+		{
+			String src = append String(sourcePath);
+			String tgt = append String(targetPath);
+
+			SourcePath = src;
+			TargetPath = tgt;
+
+			OverwriteMode = overwriteMode;
+		}
+	}
+
+	public bool ScanningFiles => !_scanQueue.IsEmpty;
+
+	[AllowAppend]
+	public this(List<String> sourcePaths, StringView targetDirectoryPath)
+	{
+		List<String> sourcePathList = append List<String>(sourcePaths.Count);
+		String targetDirectoryPathStr = append String(targetDirectoryPath);
+
+		_sourcePath = sourcePathList;
+		_targetDirectoryPath = targetDirectoryPathStr;
+
+		for (String path in sourcePaths)
+		{
+			_sourcePath.Add(new String(path));
+			_scanQueue.Add(new String(path));
+		}
+
+		_totalEntriesToCopy = sourcePaths.Count;
+	}
+	
+	public enum CopyError : IDisposable
+	{
+		case None;
+		case TargetDirectoryIsNotDirectory;
+		case SourceDoesntExist(String SourcePath);
+		case TargetFileExists(String FileName);
+		case TargetDirectoryExists(String DirectoryName);
+
+		public void Dispose()
+		{
+			switch (this)
+			{
+			case .None:
+			case .TargetDirectoryIsNotDirectory:
+			case .SourceDoesntExist(let SourcePath):
+				delete SourcePath;
+			case .TargetFileExists(let FileName):
+				delete FileName;
+			case .TargetDirectoryExists(let DirectoryName):
+				delete DirectoryName;
+			}
+		}
+	}
+
+	private Result<void, CopyError> CollectFilesToCopy()
+	{
+		void RemoveFront()
+		{
+			String path = _scanQueue.PopFront();
+			delete path;
+		}
+
+		while (!_scanQueue.IsEmpty && Running)
+		{
+			//Thread.Sleep(1000);
+
+			String currentPath = _scanQueue.Peek();
+
+			//FileInfo sourceInfo = scope FileInfo(currentPath);
+			
+			String fileName = scope .();
+			Path.GetFileName(currentPath, fileName);
+
+			String targetPath = scope .();
+			Path.Combine(targetPath, _targetDirectoryPath, fileName);
+
+			//FileInfo targetInfo = scope FileInfo(targetPath);
+
+			if (Directory.Exists(currentPath))
+			{
+				/*for (FileFindEntry e in Directory.Enumerate(currentPath))
+				{
+					String entryPath = new String();
+					e.GetFilePath(entryPath);
+					_scanQueue.Add(entryPath);
+				}*/
+			}
+			else if (File.Exists(currentPath))
+			{
+				if (File.Exists(targetPath))
+				{
+					switch (CurrentFileMode)
+					{
+					case .KeepBoth, .OverwriteFile, .Skip:
+					default:
+						return .Err(.TargetFileExists(new String(fileName)));
+					}
+				}
+
+				_pathsToCopy.Add(new CopyInfo(currentPath, targetPath, CurrentFileMode));
+				RemoveFront();
+				_nextFileMode = .None;
+			}
+		}
+
+		_totalEntriesToCopy = _pathsToCopy.Count;
+
+		return .Ok;
+	}
+
+	private CopyError _currentError = .None ~ _.Dispose();
+
+	public override RunResult Run()
+	{
+		_currentError.Dispose();
+		_currentError = .None;
+		if (CollectFilesToCopy() case .Err(out _currentError))
+		{
+			return .Pause;
+		}
+		
+		while (!_pathsToCopy.IsEmpty && Running)
+		{
+			//Thread.Sleep(1000);
+			CopyInfo currentPath = _pathsToCopy.PopFront();
+
+			defer
+			{
+				delete currentPath;
+			}
+
+			CopyPath(currentPath);
+		}
+
+		return .Finished;
+	}
+
+	private Result<void> CopyPath(CopyInfo sourcePath)
+	{
+		if (Directory.Exists(sourcePath.SourcePath))
+		{
+		}
+		else if (File.Exists(sourcePath.SourcePath))
+		{
+			bool forceOverwrite = false;
+			if (File.Exists(sourcePath.TargetPath))
+			{
+				switch (sourcePath.OverwriteMode)
+				{
+				case .KeepBoth:
+					String fileExtension = scope .();
+					Path.GetExtension(sourcePath.TargetPath, fileExtension);
+
+					String fileName = scope .();
+					Path.GetFileName(sourcePath.SourcePath, fileName);
+
+					Path.FindFreePath(_targetDirectoryPath, fileName.Substring(0..<^fileExtension.Length), fileExtension, sourcePath.TargetPath..Clear());
+				case .OverwriteFile:
+					forceOverwrite = true;
+				case .Skip:
+				default:
+					return .Err;//(.TargetFileExists);
+				}
+			}
+
+			File.Copy(sourcePath.SourcePath, sourcePath.TargetPath, forceOverwrite);
+		}
+		else
+		{
+			// TODO error
+			return .Err;
+		}
+
+		return .Ok;
+	}
+
+	public override void OnRenderPopup()
+	{
+		if (ImGui.Begin("Copying files..."))
+		{
+			if (ScanningFiles)
+			{
+				ImGui.ProgressBar(-1.0f * (float)ImGui.GetTime(), .(-1, 0), scope $"Found {_pathsToCopy.Count} files...");
+			}
+			else
+			{
+				int copiedFiles = _totalEntriesToCopy - _pathsToCopy.Count;
+
+				ImGui.ProgressBar(copiedFiles / _totalEntriesToCopy, .(-1, 0), scope $"Copied {copiedFiles} / {_totalEntriesToCopy} files.");
+			}
+
+			switch (_currentError)
+			{
+			case .None:
+				// Do nothing
+			case .TargetDirectoryIsNotDirectory:
+				// This shouldn't be possible
+				Debug.Break();
+			case .SourceDoesntExist(let SourcePath):
+				// This isn't good!
+			case .TargetFileExists(let fileName):
+				ImGui.PushStyleColor(.Text, 0xFF0000FF);
+				ImGui.TextUnformatted(scope $"A file with the name \"{fileName}\" already exists.");
+				ImGui.PopStyleColor();
+
+				if (ImGui.Button("Overwrite"))
+				{
+					_nextFileMode = .OverwriteFile;
+					Continue();
+				}
+				ImGui.AttachTooltip("Overwrites the existing file. Will ask again if another conflict occurs.");
+
+				if (ImGui.Button("Overwrite All"))
+				{
+					_allFilesMode = .OverwriteFile;
+					Continue();
+				}
+				ImGui.AttachTooltip("Overwrites all existing files.");
+
+				if (ImGui.Button("Keep both"))
+				{
+					_nextFileMode = .KeepBoth;
+					Continue();
+				}
+				ImGui.AttachTooltip("Keeps both the existing file as well as the new one, differentiates by adding a number to the name. Will ask again if another conflict occurs.");
+
+				if (ImGui.Button("Keep all"))
+				{
+					_allFilesMode = .KeepBoth;
+					Continue();
+				}
+				ImGui.AttachTooltip("Keeps both the existing files as well as the new ones, differentiates by adding a number to the name.");
+				
+				if (ImGui.Button("Cancel"))
+				{
+					Abort();
+				}
+			case .TargetDirectoryExists(let directoryName):
+				ImGui.PushStyleColor(.Text, 0xFF0000FF);
+				ImGui.TextUnformatted(scope $"A file with the name \"{directoryName}\" already exists.");
+				ImGui.PopStyleColor();
+
+				if (ImGui.Button("Combine"))
+				{
+					_nextFileMode = .CombineDirectories;
+					Continue();
+				}
+				ImGui.AttachTooltip("Merges the copied directory into the target directory. Will ask again if another conflict occurs.");
+
+				if (ImGui.Button("Combine All"))
+				{
+					_allFilesMode = .CombineDirectories;
+					Continue();
+				}
+				ImGui.AttachTooltip("Merges all copied directories into the target directories.");
+
+				if (ImGui.Button("Keep both"))
+				{
+					_nextFileMode = .KeepBoth;
+					Continue();
+				}
+				ImGui.AttachTooltip("Renames the copied directory, so that they no longer conflict. Will ask again if another conflict occurs.");
+
+				if (ImGui.Button("Keep all"))
+				{
+					_allFilesMode = .KeepBoth;
+					Continue();
+				}
+				ImGui.AttachTooltip("Renames the copied directory, so that they no longer conflict.");
+				
+				if (ImGui.Button("Cancel"))
+				{
+					Abort();
+				}
+			}
+			
+			ImGui.End();
+		}
+	}
+}
diff --git a/GlitchyEngine/src/Collections/IntrusiveLinkedList.bf b/GlitchyEngine/src/Collections/IntrusiveLinkedList.bf
new file mode 100644
index 0000000..08fe364
--- /dev/null
+++ b/GlitchyEngine/src/Collections/IntrusiveLinkedList.bf
@@ -0,0 +1,77 @@
+using System;
+using System.Collections;
+
+namespace GlitchyEngine.Collections;
+
+/*class IntrusiveLinkedList<T> : ICollection<T> where T : ILinkedListElement, var
+{
+	private T _head;
+	private T _tail;
+
+	private bool _ownsElements;
+
+	public void Add(T element)
+	{
+		element.List = this;
+		if (_head == null)
+		{
+			_head = _tail = element;
+		}
+		else
+		{
+			//_tail.ListLink.Previous = this;
+		}
+	}
+
+	public void Clear()
+	{
+
+	}
+
+	public bool Contains(T item)
+	{
+		return default;
+	}
+
+	public void CopyTo(Span<T> span)
+	{
+
+	}
+
+	public bool Remove(T item)
+	{
+		return default;
+	}
+}
+
+class ListLink<T> where T : ILinkedListElement
+{
+	public IntrusiveLinkedList<T> List { get; internal set; }
+	public ListLink<T> Previous { get; internal set; }
+	public ListLink<T> Next { get; internal set; }
+}
+
+interface ILinkedListElement
+{
+}
+
+[AttributeUsage(.Class | .Struct)]
+struct IntrusiveLinkedListAttribute : Attribute, IComptimeTypeApply
+{
+	[Comptime]
+	public void ApplyToType(Type type)
+	{
+		Compiler.EmitAddInterface(type, typeof(ILinkedListElement));
+
+		Compiler.EmitTypeBody(type, new $"""
+			//ListLink<{type}> _listLink;
+			public using ListLink<{type}> _listLink;
+			public ListLink<{type}> ListLink => _listLink;
+			""");
+	}
+}
+
+[IntrusiveLinkedList]
+class LLTest
+{
+}*/
\ No newline at end of file
diff --git a/GlitchyEngine/src/Extension/System/IO/Path.bf b/GlitchyEngine/src/Extension/System/IO/Path.bf
index 966130b..8551a4c 100644
--- a/GlitchyEngine/src/Extension/System/IO/Path.bf
+++ b/GlitchyEngine/src/Extension/System/IO/Path.bf
@@ -34,6 +34,7 @@ extension Path
 			path.Remove(0, 1);
 	}
 
+	
 	public static void Combine(String target, params StringView[] components)
 	{
 		for (var component in components)
@@ -46,4 +47,32 @@ extension Path
 
 		target.Replace(Path.AltDirectorySeparatorChar, Path.DirectorySeparatorChar);
 	}
+
+	/**
+	 * If a file with the given path ([targetDirectory]/[wantedName][fileExtension]) already exists it will add a number at the end of the file name.
+	 * @param targetDirectory The directory in which the file will be put.
+	 * @param wantedFileName The wanted name of the file. If it already exists a number will be put behind it.
+	 * @param fileExtension The file extension. This should contain the dot.
+	 * @param outFreePath The string that will contain the resulting filepath. Note: This will be cleared before writing the file name.
+	 */
+	public static void FindFreePath(StringView targetDirectory, StringView wantedName, StringView fileExtension, String outFreePath)
+	{
+		int fileNumber = 0;
+
+		String currentFileName = scope $"{wantedName}{fileExtension}";
+		while (true)
+		{
+			Path.Combine(outFreePath..Clear(), targetDirectory, currentFileName);
+			
+			FileInfo targetInfo = scope FileInfo(outFreePath);
+
+			if (!targetInfo.Exists)
+			{
+				break;
+			}
+
+			fileNumber++;
+			currentFileName..Clear().AppendF($"{wantedName} ({fileNumber}){fileExtension}");
+		}
+	}
 }
\ No newline at end of file