[Chart] Specifying sizes

[Jorden M]

I took the pie chart example from the wiki and tried to stick several copies of it into a grid, which had the effect of shrinking the charts so much you can't see the pies, just the labelling. I assume this happens with more than just pie charts. I figured there must be something I could fmap into the grid that would set the size of every chart to whatever I wanted, but I don't see anything in Pie, Grid, or Renderable with which I could override the default sizing. Am I missing something simple, or can someone tell me where I should look to make a patch?

Thanks,
-j