Without drawing the lines you can see that DP is awfully offside, but with the lines it shows that it was a very diffcult call. Saying its 100% offside or onside is very difficult.
Its not by any mean CLEARLY OFFSIDE.
Mistakes are made by refs all the time agains Juve as I'm sure it has been said in this forum many times. Thuram's red card this year agains Roma for a phantom trip. How about in the CL final against Milan when Dida was halfway out to the penalty spot before the Juve players could even take the shot? I'm tired of Inter and the other Serie A teams bitching about Juve getting special treatment by the refs.