is not supported by dot, neato and fdp for the output formats PNG, SVG, PDF etcetera.
Please implement this in such a way that the following issue:
can be closed because layering should also be applicable for clusters.
Fixing this issue will enhance the output of graphviz because edges will not run over nodes and obscuring their labels. Also being able to control nodes and edges in which layer they are presented for these output formats, will improve the quality of the graphs in general.