thank you both for the usability feedback; it's super helpful!
by the way, I've just uploaded v2.2, which fixes a few things:
- adds the animation overlay "onion skin"
- lets you choose a page background color when you export the game
- fixes the bug with "ghost rooms" in the exits panel
- fixes the bug where copied rooms continue to to be "linked" so changing one changes the other
- the player avatar can't escape off the screen to the left and right anymore
- adds ability to apply wall settings to all rooms at once