Allow context menu to show when activating scene tree with right click

Source/Editor/Windows/SceneTreeWindow.cs

@@ -26,7 +26,6 @@ namespace FlaxEditor.Windows
         private Tree _tree;
         private Panel _sceneTreePanel;
         private bool _isUpdatingSelection;
-        private bool _isMouseDown;
 
         private DragAssets _dragAssets;
         private DragActorType _dragActorType;
@@ -317,10 +316,7 @@ namespace FlaxEditor.Windows
                 return true;
 
             if (buttons == MouseButton.Right)
-            {
-                _isMouseDown = true;
                 return true;
-            }
 
             return false;
         }
@@ -331,10 +327,8 @@ namespace FlaxEditor.Windows
             if (base.OnMouseUp(location, buttons))
                 return true;
 
-            if (_isMouseDown && buttons == MouseButton.Right)
+            if (buttons == MouseButton.Right)
             {
-                _isMouseDown = false;
-
                 if (Editor.StateMachine.CurrentState.CanEditScene)
                 {
                     // Show context menu
@@ -359,14 +353,6 @@ namespace FlaxEditor.Windows
             return false;
         }
 
-        /// <inheritdoc />
-        public override void OnLostFocus()
-        {
-            _isMouseDown = false;
-
-            base.OnLostFocus();
-        }
-
         /// <inheritdoc />
         public override DragDropEffect OnDragEnter(ref Float2 location, DragData data)
         {