Great tool to start off with. This is my first time editing Prefabs outside of the game.
I've noticed that when using the fill tool the program sometimes locks up. No error or anything but becomes unresponsive and all buttons and actions become greyed out.
I've also had to redownload a few times even after updating as the Zombie.exe just seems to do nothing.
I would also like to make a suggestion to possibly add a circle tool like can be found at this site. It's worked really well for laying out some structures I've made in the past.
https://www.pixilart.com/
Thanks again!