I know this hasn't been commented on in a while, but I just found this app and am starting to use it to support some World Anvil content I am writing.
@fenixproductions, any chance you might put the source code for this on Github, so we can branch and create custom editors?
I'd like to see it enhanced so that the bbcode tags are highlighted in a different color from the plain text. That would make it much easier to read and edit. Something simple like change the foreground color of anything appearing between two square brackets to blue, red, etc.