Fix bug in CustomEditorWindow usage

#3392

Source/Editor/CustomEditorWindow.cs

@@ -33,8 +33,8 @@ namespace FlaxEditor
             private void Set(CustomEditorWindow value)
             {
                 _customEditor = value;
-                _presenter.Select(value);
                 _presenter.OverrideEditor = value;
+                _presenter.Select(value);
             }
 
             /// <inheritdoc />

Source/Editor/CustomEditors/CustomEditorPresenter.cs

@@ -132,6 +132,8 @@ namespace FlaxEditor.CustomEditors
                 get => _overrideEditor;
                 set
                 {
+                    if (_overrideEditor == value)
+                        return;
                     _overrideEditor = value;
                     RebuildLayout();
                 }
@@ -200,7 +202,6 @@ namespace FlaxEditor.CustomEditors
             protected override void Deinitialize()
             {
                 Editor = null;
-                _overrideEditor = null;
 
                 base.Deinitialize();
             }