As we all know, the second expansion is coming up, and there will be a major patch released ahead of the expansion itself to prepare all players for the new content. This patch will contain the new skills (up to level 70), talents, and many other class and game mechanics changes.
In this thread I will consolidate information about known changes to the user interface, to give everyone time to prepare themselves. I will update it as additional information presents itself.
From discussion on the UI & Macros forum, it does not appear that Blizzard intends to overhaul the user interface for 3.x in the same way they did for 2.x, which required nearly every addon to be rewritten, in some cases from scratch. However, there are some structural changes that they are making within the Lua interpreter that will likely break any addon that isn't properly modified.
So the big question is: will all addons need to be updated for 3.x? The answer is: almost certainly, but unlike in 2.x, the changes won't be very dramatic, and many addons will make the transition with minimal work from their authors.
For those who care about the details, the major changes are:
- Blizzard code will use an improved Lua calling methodology that will require most user code hooking API functions to be modified.
- The handling of font objects embedded in buttons will be changed.
- Secure state headers are being completely overhauled, which affects most addons that conditionally display or update secure UI objects in combat.
- The tradeskill UI is being overhauled.
There is one major addition to the UI in 3.0 that bears discussion: the threat meter. Until now, addon writers have basically had to guess at the threat each effect and ability generates (or removes). Their guessing has been pretty accurate given the methods used, but it's still not a perfect, 100% accurate picture, and becomes distinctly blurry if players are not all running compatible threat meter addons or are far enough away from each other that the combat log doesn't record everything.
The other downside to threat meter addons is that they consume a very significant amount of CPU time processing the combat log so they can do their job. And all of this pales beside the most critical issue: if you don't have an updated threat meter addon, you're basically hosed in endgame raiding. Many raid encounters are so threat-sensitive that even exceeding the tank's threat, much less pulling aggro, can mean a near-instant wipe.
Thus, in 3.0, Blizzard will resolve this issue by exposing threat values directly within the client API. There will even be a built-in threat meter in the standard UI, so that nobody will have to download an addon if they don't want to. (However, the current implementation of the threat meter in beta is very bare-bones and somewhat ugly to boot.)
The upshot is that the guts of Omen and KTM (and any other threat meters out there) will be completely scrapped, and they will merely be used to display the threat data provided by the client. This will make them both much smaller and dramatically less CPU-intensive.