[wurmfood]

It does include it, though it may not be as exact.

The Castbar element supports the .SafeZone sub element, which can be added and will give an approximate "safe zone" based on current latency. I added it to my layout with this:

if(unit == 'player') then
	self.Castbar.SafeZone = self.Castbar:CreateTexture(nil,'OVERLAY')
	self.Castbar.SafeZone:SetTexture(texture)
	self.Castbar.SafeZone:SetVertexColor(.69,.31,.31)
end

It's not perfect, but it's close. Note that you don't have to set the positioning for the texture, as the element sets it when a spell is being cast.