If you've ever used CuteFTP 4 or (more likely to recognize function from) dreamweaver ultradev or MX, when editing source notepad style, there is mild highlighting(which you've already handled) and also in situations where you start part of a code a small box drops down listing possible completions of the code you are inputting.
Example:

Now I don't know if this is what you are talking about by EZ-Functions, but this seems relatively useful. I imagine it would get beginning asl coders more into doing things by hand as they'd have a little inspiration/nudge towards the right direction of where they could take their code. I can't say for all syntax, but for situations like...
if | is
| not
| exists
| property
| etc.
I don't know if I would use it, but it'd help out during some of those sessions where you sit and think, "what now, what now, how should I do this?" For most functionality/ease of use I'd fix it to a "shift" key (not necessarily shift, but a key that places priority onto the menu. I think that makes sense) and operate navigating the menu's with up and down keys.
Eh, I don't know, just an idea.