I'm currently tackling the creation of an options configuration GUI for my Alerter mod (will upload here for the next version... when the GUI is done). It's the first GUI I've ever tried creating, and boy can it be a pain to debug sometimes.
I'd like to share a tip that will hopefully save some of the rest of you a few hours of grief.
Get an XML parser/linter ASAP!!! I've only found one specifically designed for WoW XML, and it's called AddonEditor (google to find it on curse-gaming or worldofwar).
The reason this will save you hours of troubleshooting is simple. If your XML file contains one little tiny error (such as leaving out an '=', doh), nothing in the XML file will load. And then you'll wonder why you're getting all kind of strange Lua errors in your OnLoad routine... well, yeah, if your Lua is referring to a frame which wasn't loaded, Error!
So yeah. That's my mod author tip of the day. Hope it helps someone... otherwise I'll look like a flaming n00b.
