Searched on this for a hour and finally found it under "steps"...searched for "stairs" ;-)
anyways...I now need the opposite of the implemented method :-(
unfortunately one can't decide which way one wants to have to corners arranged. I try to visualize this a little bit: (an x implies a sample/data point)
..........x------|........|------x
..........|........|........|........|
..........|........x.......|........|----x
x-------|................x
step:true what I need

may the implementation could be extended to have an option like "first edge rising: true"

Cheers
Stefan