First of all, I just wanted to let you know I'm *very* grateful to you for even wanting to develop Rift addons. I am a fellow developer and I can tell you that, as a fellow new Rift player as well I have noticed the small number of addons and even smaller number that are updated past 2013. At least compared to WoW, GW2 and several other games that are no more popular than Rift. It's a sobering thought, but my motivation is rekindled when I see how popular Rift is while playing! I'm hooked, and want to help renew interest in the Rift addon development community. So I am grateful you and the few other active developers out there haven't given up or, in your (and my) case are starting. =) Thanks and good luck.
As to your idea, I second EmilMac in that that sounds like a *beautiful* idea and I'd love something like that myself. I would like to give you an idea. You may have already heard of it, but there is an application called Overwolf that lets you run different little apps while you're playing games. It has a Web browser (to look things ups while playing without having to Alt-Tab out) and a few others, several skins for the small, unobtrusive in-game dock, and a "store" that lets you download and install many other apps, including chat apps, social media apps (watch YouTube or Face Book while you play), utility apps (like a calculator or CPU/system monitor) and many other types.
But here's the part relevant to you. There is a music player app that lets you create your own playlists and listen to them in-game. Now I know that's not exactly what you're looking for, but I'm just thinking there might be something similar to that as another option if you can't figure out how to code an addon yourself for Rift. I have the utmost faith in your abilities, but just in case the API doesn't support that type of I/O or something similar, it's another option.
Also, I'm fairly certain that, like WoW, the Rift addon development APIs use Lua
as interface languages to develop addons, so if you need any information on addon development you can look for tutorials or reference dealing with those languages. Also, the Official Rift Forums
is a great place to look for help getting started and pointers to other resources, as well as this site, RiftUI, and Curse
is the other place to find information as well as addons and skins.
Finally, another good source of information in learning to develop addons is the source itself (The Source, Luke. Use the Source! And the Sourcestone! xP) As in any type of programming, when getting started it can help to look at source code for other addons (as long as you follow the addon developer's license agreement, of course), and the addons are simply zip files containing Lua, XML, logo image and other files, so it's easy to learn how things work if you use an addon and then look at the source code to see what does what.
Anyway, I wish you luck and once again you have my gratitude and respect for joining the addon development community (esp. since I'm new here too and now I don't feel so alone xP). Happy Holidays and gl in your endeavors. I love your idea! =D