Steps to reproduce:
1. Place an object, let's say, an exit.
2. Place another object, let's say, a window.
3. Set both to have No Overwrite.
4. Place the window and the exit so that they are overlapping each other.
The object that is in front in terms of object order (in this case, the window; which could change by playing with the "To Front" / "To Back" buttons) should be displayed behind the other object. Instead, it's displayed in front. (Compare to how it looks in-game, which DOES draw them correctly.)
I'm not sure how the editor actually renders objects. If it uses a similar process to the game itself - ie: draws No Overwrite and regular objects on seperate layers, which are then combined into the final image - the correct effect would be achieved by rendering the objects on the No Overwrite layer in reverse order.
Thanks. This is fixed in the next editor version.