> Two things we noted.
> mixing tags together means broken.
> 
>  [i][b]text[/i][/b] does not work.
>  [i][b]text[/b][/i] works.
> 
> Hiders seem to work well even nested. As does color, both text and hexadecimal.
> Combinations of basic formatting also works. (bold/italic/underlined)

I've been working on a validation system that gives helpful errors:

![](https://dl.dropboxusercontent.com/spa/quq37nq1583x0lf/2duzeioa.png)

The BBCode implementation I'm using only exposes two vague types of errors, one of them being that "some tags appear to be misaligned" error above. I had to implement the rest of the errors in that screenshot.

Unfortunately, fixing tag misalignment is a pretty hard problem if the parser itself doesn't expose that feature.

Fortunately, the parser seems to handle things like misalignment well in that, instead of choking, it just simply doesn't render the misaligned BBCode into HTML. Bad tags and misaligned tags just remain unrendered plaintext for you to fix. 

Hopefully between that and my validation error messages, it won't be too hard to debug a BBCode clusterfuck. 

People writing format-heavy posts should have a decent feedback loop by clicking the Preview button periodically which triggers my error reporting system. (I'll deploy it to the dev server later tonight)