Omen Threat Meter

Description
Omen is a threat meter.

Basically, enemies in WoW decide who to attack by deciding who is the most threatening based on the abilities you use. What Omen does is provide accurate values of your group's relative threat level on individual enemies, so that you can see when you're in danger of pulling aggro (or, if you're next on the snack list if your tank bites it). This info is usually only critical in raids, where only tanks can survive aggro, but it's useful for any multi-player situation.
Changes from version v3.0.7 to v3.0.8

* Fix GetShapeShiftFormInfo() error that occurs for DKs when they aren't in any presence. This occurs when they respec between their primary/secondary specs and the game drops them out of all presences and subsequently enter combat presence-less.
* Add ConfigMode support (see addon OneButtonConfig).
* Omen will now update its bars immediately on showing from a hidden state instead of updating on the next threat event.
* Includes updates to all localizations via http://www.wowace.com/projects/omen-threat-meter/localization/

FAQ
How is Omen3 different from Omen2?

Omen3 relies completely on the Blizzard threat API and threat events. It does not attempt to calculate or extrapolate threat unlike Omen2.

Omen2 used what we called the Threat-2.0 library. This library was responsible for monitoring the combat log, spellcasting, buffs, debuffs, stances, talents and gear modifiers for calculating each individuals threat. Threat was calculated based on what was known or approximated from observed behaviors. Many abilities such as knockbacks were just assumed (to be a 50% threat reduction) as they were mostly impossible to confirm.

The Threat-2.0 library also included addon communication to broadcast your threat to the rest of the raid as long as they were also using Threat-2.0. This data was then used to provide a raid wide display of threat information.

Since patch 3.0.2, Omen no longer does any of these things and the need for a threat library is no longer necessary. Omen3 uses Blizzard's new in-built threat monitor to obtain exact values of every members threat. This means Omen3 has no need for synchronisation of data, combat log parsing or guessing, resulting in a significant increase in performance with regards to network traffic, CPU time and memory used. The implementation of boss modules for specific threat events (such as Nightbane wiping threat on landing) are also no longer necessary.

Further benefits of this new implementation include the addition of NPC threat on a mob (eg, Human Kalecgos). However, there are some drawbacks; frequency of updates are much slower, threat details cannot be obtained unless somebody in your party/raid are targetting the mob and it is also not possible to obtain threat from a mob you are not in direct combat with.
How do I get rid of the 2 vertical gray lines down the middle?

Lock your Omen. Locking Omen will prevent it from being moved or resized, as well as prevent the columns from being resized. If you haven't realized it, the 2 vertical gray lines are column resizing handles.
How do I make Omen3 look like Omen2?

Change both the Background Texture and Border Texture to Blizzard Tooltip, change the Background Color to black (by dragging the luminance bar to the bottom), and the Border Color to blue.
Why does no threat data show on a mob when I target it even though it is in combat?

The Blizzard threat API does not return threat data on any mob you are not in direct combat with. We suspect this is an effort on Blizzard's part to save network traffic.
Is there ANY way around this Blizzard limitation? Not being able to see my pet's threat before I attack has set me back to guessing.

There is no way around this limitation short of us doing the guessing for you (which is exactly how Omen2 did it).

The goal of Omen3 is to provide accurate threat data, we no longer intend to guess for you and in the process lower your FPS. Have some confidence in your pet/tank, or just wait 2 seconds before attacking and use a low damage spell such as Ice Lance so that you can get initial threat readings.
Can we get AoE mode back?

Again, this is not really possible without guessing threat values. Blizzard's threat API only allows us to query for threat data on units that somebody in the raid is targeting. This means that if there are 20 mobs and only 6 of them are targeted by the raid, there is no way to obtain accurate threat data on the other 14.

This is also extremely complicated to guess particularly for healing and buffing (threat gets divided by the number of mobs you are in combat with) because mobs that are under crowd control effects (sheep, banish, sap, etc) do not have their threat table modified and addons cannot reliably tell how many mobs you are in combat with. Omen2's guess was almost always wrong.
The tooltips on unit mouseover shows a threat % that does not match the threat % reported by Omen3. Why?

Blizzard's threat percentage is scaled to between 0% and 100%, so that you will always pull aggro at 100%. Omen reports the raw unscaled values which has pulling aggro percentages at 110% while in melee range and 130% otherwise.

By universal agreement, the primary target of a mob is called the tank and is defined to be at 100% threat.
Does Omen3 sync or parse the combat log?

No. Omen3 does not attempt to sync or parse the combat log. Currently there are no intentions to do so.
The threat updates are slow...

Omen3 updates the threat values you see as often as Blizzard updates the threat values to us.

In fact, Blizzard updates them about once per second, which is much faster than what Omen2 used to sync updates. In Omen2, you only transmitted your threat to the rest of the raid once every 3 seconds (or 1.5s if you were a tank).