I would like to see a feature to mirror a custom model in the custom editor. This would help those of us who sometimes forget it's mirror image while filling in a piece of coro. Then get to the end and realize the mistake. My fingers hurt enough.

It's pretty easy to do. Read each line in of the model and print the line backwards.
Call it paste mirror image. That should correct the model to work as expected in xlights then.
I wrote a perl script to do it for my mornings mix up....
Thank you,
Jason