thanks for your comment Mike,
I understand why you get this idea, but I am not using cables at all,
the point where i measure is directly on the input of the 2 first digital channels, and at that same point is where the scope prope is attached,
so the digital part, can not see any ringings that i would not have seen on analogs.
pcb is populated with : 120R in series with 100k // 8.2pF
if I add another scope probe, and change the zero of analog ch 2, the two analog curves align perfectly, and there is no jitter between the two, as expected.
the ahead time of digital is 16nS (and full of jitter) and can be compensated for in the digital menu, (but dont affect the jitter) this works fine as long as the trigger is analog.
IF the trigger is digital (and you are not unint analogs at all) the deskew adjustment dont work.
but in that case the delay trigger can be used to get it all back on track,
it is no big deal as long as you know what you are playing with.
but another day i need to work on real signals, it could be cool if the scope was in zero when i read zero on curves :-)