I played a few days with it...very nice addon indeed.
I play AV alot and noticed the following:
I have all the group on the left side in two vertical rows of 4 groups each row.
From the side of the 2nd vertical row, all the way to the right side and bottom of my entire screen, often gets a rectangular, transparant color, covering everything.
The colors are the same ones as the Class-colors.
And often it flashes and often the color changes to another Class color.
It just occupies a part of my lower screen mostly for a few secs, and then suddenly it will be gone again.
It is very annoying cus right now it happens all the time when I am in AV battleground.
I tried a new install, but alas, it happened again :(
So I dont know what to do now. I hope you can solve this.
You could probably use a combination of XRaidStatus/RABuffs (to monitor party/raid buffs of your choosing), Decursive (to show curable party/raid debuffs), and Elkano's Buff Bars (to show target buffs). It may also be possible to eliminate the issue by tweaking some of the Aura options scattered around in Pitbull, which may also help narrow down the problem.
I think I've seen this happen maybe twice ever (in months of running Pitbull). From what I can recall, I think it only happened to me those times when the 5th party member joined. I'm thinking a map show & hide cleared it up, but it's been a while since I've had it happen, so I can't remember for certain.