Add **Behavior Tree** asset type and editing

Source/Editor/Content/Proxy/BehaviorTreeProxy.cs

@@ -0,0 +1,66 @@
+// Copyright (c) 2012-2023 Wojciech Figat. All rights reserved.
+
+using System;
+using System.IO;
+using FlaxEditor.Content.Thumbnails;
+using FlaxEditor.Windows;
+using FlaxEditor.Windows.Assets;
+using FlaxEngine;
+using FlaxEngine.GUI;
+
+namespace FlaxEditor.Content
+{
+    /// <summary>
+    /// A <see cref="BehaviorTree"/> asset proxy object.
+    /// </summary>
+    /// <seealso cref="FlaxEditor.Content.BinaryAssetProxy" />
+    [ContentContextMenu("New/AI/Behavior Tree")]
+    public class BehaviorTreeProxy : BinaryAssetProxy
+    {
+        /// <inheritdoc />
+        public override string Name => "Behavior Tree";
+
+        /// <inheritdoc />
+        public override bool CanReimport(ContentItem item)
+        {
+            return true;
+        }
+
+        /// <inheritdoc />
+        public override EditorWindow Open(Editor editor, ContentItem item)
+        {
+            return new BehaviorTreeWindow(editor, item as BinaryAssetItem);
+        }
+
+        /// <inheritdoc />
+        public override Color AccentColor => Color.FromRGB(0x3256A8);
+
+        /// <inheritdoc />
+        public override Type AssetType => typeof(BehaviorTree);
+
+        /// <inheritdoc />
+        public override bool CanCreate(ContentFolder targetLocation)
+        {
+            return targetLocation.CanHaveAssets;
+        }
+
+        /// <inheritdoc />
+        public override void Create(string outputPath, object arg)
+        {
+            if (Editor.CreateAsset(Editor.NewAssetType.BehaviorTree, outputPath))
+                throw new Exception("Failed to create new asset.");
+        }
+
+        /// <inheritdoc />
+        public override void OnThumbnailDrawBegin(ThumbnailRequest request, ContainerControl guiRoot, GPUContext context)
+        {
+            guiRoot.AddChild(new Label
+            {
+                Text = Path.GetFileNameWithoutExtension(request.Asset.Path),
+                Offsets = Margin.Zero,
+                AnchorPreset = AnchorPresets.StretchAll,
+                Wrapping = TextWrapping.WrapWords
+            });
+        }
+    }
+}