how do you learn to extend default UI?

[jeskeca]

I'm a skilled computer programmer, and know Lua/XML, etc very well. However, I'm not very familiar with the APIs or "DOM" inside WoW UI.

I would like to make a mod that adds some text next to playernames most places they appear in tables. For example, in:

- guild info table
- LFM 'players in queue' table
- player tooltips (when you mouseover a player name)

I see lots of mods that replace entire UI components, and relatively few that change existing components. When I look at the mods that change existing components, I am lost as to how: (a) they found the name of the UI window to change, (b) they learned the names of the elements within the windows, (c) they patch their new elements into the existing window.

Is there some howto that explains how to patch an existing UI window? If not, how do you learn to do it? Are people reading Bliz UI source code? Is there a popular 'dev-mod' that lets you inspect the UI DOM for existing UI elements?

[Tunga]

As a start, if you grab Blizzard's UI toolkit it will extract all of the source code for the default interface. Alternatvely you can find most of it on www.wowwiki.org .

[Jumpy]

I started by scanning and absorbing all I could from http://www.wowwiki.com/Interface_Customization. I also downloaded the User Interface Customization tool at http://www.blizzard.com/support/wow/?id=aww01669p and I downloaded other addons that came close to what I wanted to do and studied them.