You're breathtaking!

Source/Editor/Viewport/Modes/EditorGizmoMode.cs

@@ -0,0 +1,67 @@
+// Copyright (c) 2012-2020 Wojciech Figat. All rights reserved.
+
+using System;
+using FlaxEngine;
+
+namespace FlaxEditor.Viewport.Modes
+{
+    /// <summary>
+    /// Editor viewport gizmo mode descriptor. Defines which gizmo tools to show and how to handle scene editing.
+    /// </summary>
+    /// <remarks>
+    /// Only one gizmo mode can be active at the time. It defines the viewport toolset usage.
+    /// </remarks>
+    [HideInEditor]
+    public abstract class EditorGizmoMode
+    {
+        private MainEditorGizmoViewport _viewport;
+
+        /// <summary>
+        /// Gets the viewport.
+        /// </summary>
+        public MainEditorGizmoViewport Viewport => _viewport;
+
+        /// <summary>
+        /// Occurs when mode gets activated.
+        /// </summary>
+        public event Action Activated;
+
+        /// <summary>
+        /// Occurs when mode gets deactivated.
+        /// </summary>
+        public event Action Deactivated;
+
+        /// <summary>
+        /// Initializes the specified mode and links it to the viewport.
+        /// </summary>
+        /// <param name="viewport">The viewport.</param>
+        public virtual void Init(MainEditorGizmoViewport viewport)
+        {
+            _viewport = viewport;
+        }
+
+        /// <summary>
+        /// Releases the mode. Called on editor exit or when mode gets removed from the current viewport.
+        /// </summary>
+        public virtual void Dispose()
+        {
+            _viewport = null;
+        }
+
+        /// <summary>
+        /// Called when mode gets activated.
+        /// </summary>
+        public virtual void OnActivated()
+        {
+            Activated?.Invoke();
+        }
+
+        /// <summary>
+        /// Called when mode gets deactivated.
+        /// </summary>
+        public virtual void OnDeactivated()
+        {
+            Deactivated?.Invoke();
+        }
+    }
+}