I enjoyed the game very much.
A couple issues: Editor does make my Mac show the spinning beach ball when placing portals. Player start location is not updated when you move the start zone. Save button doesn’t indicate things getting saved. Player also feels like it moves a little fast, some of the platforming gets a little frustrating for me at times (from the built-in stages)
Other than that, great work!
Here’s a simple level I created:
Simple is Better / 03EE0EA