- Added IsActive state to boxes

- Replaced box.enabled with box.isActive on some nodes
- Made connection lines draw with alpha when connected box is inactive

Source/Editor/Surface/Elements/Box.cs

@@ -41,6 +41,11 @@ namespace FlaxEditor.Surface.Elements
         /// </summary>
         protected bool _isSelected;
 
+        /// <summary>
+        /// The is active flag for the box. Unlike <see cref="FlaxEngine.GUI.Control.Enabled"/>, inactive boxes can still be interacted with, they just will be drawn like disabled boxes
+        /// </summary>
+        protected bool _isActive = true;
+
         /// <summary>
         /// Unique box ID within single node.
         /// </summary>
@@ -180,6 +185,15 @@ namespace FlaxEditor.Surface.Elements
             }
         }
 
+        /// <summary>
+        /// Gets or sets the active state of the box. Unlike <see cref="FlaxEngine.GUI.Control.Enabled"/>, inactive boxes can still be interacted with, they just will be drawn like disabled boxes
+        /// </summary>
+        public bool IsActive
+        {
+            get => _isActive;
+            set => _isActive = value;
+        }
+
         /// <inheritdoc />
         protected Box(SurfaceNode parentNode, NodeElementArchetype archetype, Float2 location)
         : base(parentNode, archetype, location, new Float2(Constants.BoxSize), false)