I've been using netbeans for a couple of years now, mainly on PHP / CakePHP projects.
Recently I've started using Coldfusion, which isn't directly supported. I've found, however, that if I use PHP as a project type, I can load the files and the HTML Renderer does an admirable job with the Coldfusion tags.
I want to make it better and help the renderer to understand some of the tags and, hopefully, thereby improve code indentation and syntax highlighting.
My question, then, is how can I access the HTML dictionary to extend the vocabulary?
NB: This isn't a 'which IDE' question so don't recommend them. I want to know if and how I can achieve this in NetBeans and only Netbeans.
Here are a few ideas. If you render it in HTML, you could probably add a custom name space to the HTML. If setup correctly it can help NetBeans realize that the tags are valid and shouldn't show as an error. It might not give you all the preview and WYSIWYG functionality, but it may be better than what you are getting now. I have only done this on other platforms, but I'm pretty sure NetBeans supports it.
Also I think that NetBeans will let you add CustomTags doing something like this: http://wiki.netbeans.org/CustomTagActions