Option for display node time as percentage of parent

[kisielk]

A lot of times I'm more interested in how much time a node took as a proportion of its parent's cumulative time rather than the total graph. Right now I usually calculate it by dividing the percentage total time of the child by the percentage total time of the parent. It would be great if there was an option to display (and maybe colour) the graph this way. If it was a label it could be in addition to one of the existing labels.