Would it be possible to allow to print values inside bar segments in stacked bar chart?

[pmalek]

I'd like to print concrete values inside stacked bar chart just like so (legend not relevant on the plot):

I realize that this is most likely not possible as of now, but if I'd like to contribute something like this:

• would you be interested?
• is it possible with current renderer? Any directions for this?

[pdt256]

I added support for stacked bar chart labels in #114