Wondering if it would be possible for an addon to change the look and feel of say/yell chat bubbles. Would be solely for aesthetic purposes, just the ability to change font, size, shape of bubble, and anything else along those lines.
AFAIK, the chat bubbles work like nameplates--they're valid 'frames' but not handled Lua-side. Because of this modifying them isn't really a simple straight-forward thing--you'll have to actually scan for the frames and keep tabs on them. But it's entirely possible, yes.