[Waky]

Writing one, just a sec.

Edit:

-- OnLoad
self:RegisterEvent("UNIT_TARGET")


-- OnEvent
if (event=="UNIT_TARGET") then
local _, class = UnitClass("target")
	if (class=="DEATHKNIGHT") then
		self.bg:SetVertexColor(0.77, 0.12, 0.23, self.bg:GetAlpha())
	elseif (class=="DRUID") then
		self.bg:SetVertexColor(1,0.49,0.04, self.bg:GetAlpha())
	elseif (class=="HUNTER") then
		self.bg:SetVertexColor(0.67,0.83,0.45, self.bg:GetAlpha())
	elseif (class=="MAGE") then
		self.bg:SetVertexColor(0.41,0.8,0.94, self.bg:GetAlpha())
	elseif (class=="PALADIN") then
		self.bg:SetVertexColor(0.96,0.55,0.73, self.bg:GetAlpha())
	elseif (class=="PRIEST") then
		self.bg:SetVertexColor(1,1,1, self.bg:GetAlpha())
	elseif (class=="ROGUE") then
		self.bg:SetVertexColor(1,0.96,0.41, self.bg:GetAlpha())
	elseif (class=="SHAMAN") then
		self.bg:SetVertexColor(0,0.44,0.87, self.bg:GetAlpha())
	elseif (class=="WARLOCK") then
		self.bg:SetVertexColor(0.58,0.51,0.79, self.bg:GetAlpha())
	elseif (class=="WARRIOR") then
		self.bg:SetVertexColor(0.78,0.61,0.43, self.bg:GetAlpha())
	end
end