What UI framework did you use?
I've did some tests with BF Designer and I'm impressed!
It has a much better approach to syntax highlight than my own BF IDE.
It resisted the stress tests very well.
The snippets feature is a real surprise. Reminds me of my work building a compiler which generates brainfuck code. Oh! The time I spent at brainfuck algorithms.
But congratulations, it seems really good. Plus it is also cross-platform!!