Hi,
I glanced through this thread, but wanted to make a suggestion. I came across this interesting feature of Mozilla--another open source and prominent project which uses another language PHP programmers are probably more likely to know (or should know given that it is complementary with PHP)--javascript
:
http://kb.mozillazine.org/Midas
Given that it can handle WYSIWYG, I imagine that it could also be made to provide syntax-coloring (albeit with text)--one feature I didn't see in the example editors at the page provided above. I think having an IDE that was REALLY accessible for people to modify, like something written in these languages that many PHP folks like myself have already been using for some time would be especially nice.
Another benefit of this approach is that there is also already code written for it. But again, the biggest benefit, in my opinion, is that it could be modified by PHP users too. And since it is client-side, one could have the option to save files with it on one's own computer (assuming PHP were installed)--modifying the code as desired.
I think Smarty syntax coloring and code insertion would also be a big plus.
thanks for listening,
Brett